Which hole do I put it in? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Solver · 03-06-2003, 01:48 PM

Got a 3/4 ton longhorn with th400 tranny and it originally had a 402.
Now I am putting it back together and using a 350 engine.
The tranny crossmember was in the midlle poisition of holes.
Do I need to move it(tranny crossmember) forward to the front holes for the 350 engine?If I do this will the drive shaft lenght still be ok or did they make a different driveshaft for the 350/400 combo compared to the 402/400 combo? Got the cab off so I can't use that as a reference. Will be using HEI so I don't want to be to tight on firewall. Also want the 350 fan shroud to line up right.
Thanks

benwantland · 03-06-2003, 02:19 PM

oh, you're talking about your truck... I saw the title and thought, well, nevermind.......... I can't really help you on this one.

crazy longhorn · 03-06-2003, 02:27 PM

the 350/400 combo is mounted foward from the 402/400 , when using the fact SB stands. I couldnt say just how much, but it will affect the lenght of the D shaft. My 383/400 is mounted in 6/250 position, so I cant helptoo much on bolt spacing. Good luck,crazyL

**1970 CST Short Wide** · 03-06-2003, 02:31 PM

Ask Desert Rat. Look him up in members and e-mail him. He can most likely answer your ?

junkyardjohn · 03-06-2003, 02:57 PM

I'M NOT SURE ABOUT LONGHORNS (I'VE NEVER BUILT ONE) BUT I'VE SWITCHED SEVERAL SWB TRUCKS FROM A BB TO A SB & VISA-VERSA WITH T-400 TRANNYS, & THEY'VE ALL LINED UP GREAT WITH THE MOTOR IN THE 6 CYL. POSITION. I ALWAYS LIKE TO PUT SMALLBLOCKS IN THE 6 CYL. POS. FOR MUCH BETTER WEIGHT TRANSFER, HANDLEING ,& TRACTION. IT'S AMAZING WHAT MOVING THE MOTOR BACK A COUPLE OF INCHES WILL DO, IN THE WAY OF PERFORMACE. & NO CLEARANCE ISSUES WITH A STOCK GM HEI & THE FIREWALL.

matt67350 · 03-06-2003, 03:03 PM

fits good in both!

Slammed67 · 03-06-2003, 03:31 PM

I'd try the front hole first and if all goes well, try the rear one....... just take it nice and slow. Don't wanna force it!

(Sorry)

**Classic Heartbeat** · 03-06-2003, 03:59 PM

Engine, front set of holes with small block frame towers and transmission crossmember goes in the same holes that they were in for the big block if I remember write. If I were you I wouldn't bolt the tranny crossmember untill after the transmission is installed, then the crossmember will align itself in the correct holes. Just a thought, thats what I do. Also if that is a 72 Longhorn, I would trade you some cash and a set of small block V-8 frame towers for the Big Block ones. Let me know if you are interested. WES www.ClassicHeartbeat.com

crazy longhorn · 03-06-2003, 06:23 PM

OK.....I have 3 sets of bolt holes on the frame of my longhorn for the auto trans crossmember. As far as I know(i could be off on this), the longhorns only came with either a 400 turbo , or a 4spd. the 4 spd did not have a crossmember under the trans(bell mount). My 383 is mounted in I 6 position, & uses the rear set of holes(short tail 400 turbo, just like factory). If you use the front set of holes , you are V8 SB position(factory position & stands). There are 3 1/2 " difference from fact V8 SB, & I 6 position. I havent done a BB swap(not Chev anyway), but assume that the other set of holes are for the BB(SB ,foward holes......I6 rear holes,& BB in between).......my thoughts are that the BB is set back from SB location(a couple inches), to help with the extra lenght on the nose. The measure from the eng mount, to the bell is the same distance on the SB as it is on the BB, so you should be able to use any of the sets of holes to mount(provided that the parts clear the firewall. To the best of my knowledge, this info is correct....... crazyL

casey · 03-08-2003, 12:56 PM

That sounds like a hole lot of lovin going on Couldn't help it sorry lol

03-06-2003, 01:48 PM	#1
Solver Registered User Join Date: May 2000 Location: Storm Lake, Ia Posts: 1,449	Which hole do I put it in? Got a 3/4 ton longhorn with th400 tranny and it originally had a 402. Now I am putting it back together and using a 350 engine. The tranny crossmember was in the midlle poisition of holes. Do I need to move it(tranny crossmember) forward to the front holes for the 350 engine?If I do this will the drive shaft lenght still be ok or did they make a different driveshaft for the 350/400 combo compared to the 402/400 combo? Got the cab off so I can't use that as a reference. Will be using HEI so I don't want to be to tight on firewall. Also want the 350 fan shroud to line up right. Thanks __________________ 1972 Cheyenne Super 20 LWB-Blue 1972 Cheyenne Super 10 LWB-Black 1972 Cheyenne Super 10 LWB-Red 1972 Cheyenne Super 10 LWB-green 1972 GMC 4x4 LWB-White 1971 Cheyenne 10 LWB-Ochre 1971 Cheyenne 20 Longhorn-Copper 1971 Cheyenne 20 Longhorn-Black 1969 Custom 10 LWB-lt blue 1968 GMC 3/4 ton-green 1968 1/2 ton swb stepside-silver 1967 Chevrolet CST 10 LWB-green 1967 Chevrolet custom 20 LWB-Maroon

03-06-2003, 02:31 PM	#4
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,185	Ask Desert Rat. Look him up in members and e-mail him. He can most likely answer your ? __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

03-06-2003, 02:57 PM	#5
junkyardjohn Registered User Join Date: Aug 2001 Location: SOMERSET KY. Posts: 6,425	I'M NOT SURE ABOUT LONGHORNS (I'VE NEVER BUILT ONE) BUT I'VE SWITCHED SEVERAL SWB TRUCKS FROM A BB TO A SB & VISA-VERSA WITH T-400 TRANNYS, & THEY'VE ALL LINED UP GREAT WITH THE MOTOR IN THE 6 CYL. POSITION. I ALWAYS LIKE TO PUT SMALLBLOCKS IN THE 6 CYL. POS. FOR MUCH BETTER WEIGHT TRANSFER, HANDLEING ,& TRACTION. IT'S AMAZING WHAT MOVING THE MOTOR BACK A COUPLE OF INCHES WILL DO, IN THE WAY OF PERFORMACE. & NO CLEARANCE ISSUES WITH A STOCK GM HEI & THE FIREWALL. __________________ junkyardjohn 69 1 TON TOW TRUCK // 84 4WD CUCV BLAZER// 85 1 TON 4WD STAKE TRUCK// 86 M1031 5/4 TON 4WD CUCV// ALOT OF OLD TRUCKS FOR ONE OLD MAN TO DRIVE. THERES ROOM FOR ALL OF GODS CREATURES RIGHT NEXT TO MY MASHED POTATOES// LIFE MEMBER OF P.E.T.A (PEOPLE EATING TASTY ANIMALS) DON'T RENT U-HAUL ALWAYS TELL THE TRUTH IT WILL AMAZE PART OF THE PEOPLE & ASTONISH THE REST

03-06-2003, 03:03 PM	#6
matt67350 Registered User Join Date: May 2001 Location: Benbrook, TX Posts: 1,060	fits good in both! __________________ 69 swb stepside, rebuild and upgrade in progress

03-06-2003, 03:31 PM	#7
Slammed67 Progress = 0% Join Date: Nov 2001 Location: Kansas City, MO Posts: 2,108	I'd try the front hole first and if all goes well, try the rear one....... just take it nice and slow. Don't wanna force it! (Sorry) __________________ Jason - '67 GMC swb \| '57 Bel-Air 4dr hardtop \| '56 210 4dr Wagon \| 2000 GMC Sierra

03-06-2003, 02:19 PM	#2
benwantland Registered User Join Date: Oct 2002 Location: Iowa Posts: 71	oh, you're talking about your truck... I saw the title and thought, well, nevermind.......... I can't really help you on this one.

03-06-2003, 02:27 PM	#3
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	the 350/400 combo is mounted foward from the 402/400 , when using the fact SB stands. I couldnt say just how much, but it will affect the lenght of the D shaft. My 383/400 is mounted in 6/250 position, so I cant helptoo much on bolt spacing. Good luck,crazyL

03-06-2003, 03:59 PM	#8
Classic Heartbeat Project Junkie! Fishing Poor!! Join Date: Dec 1999 Location: Olympia,Wa. 98512 Posts: 10,766	Engine, front set of holes with small block frame towers and transmission crossmember goes in the same holes that they were in for the big block if I remember write. If I were you I wouldn't bolt the tranny crossmember untill after the transmission is installed, then the crossmember will align itself in the correct holes. Just a thought, thats what I do. Also if that is a 72 Longhorn, I would trade you some cash and a set of small block V-8 frame towers for the Big Block ones. Let me know if you are interested. WES www.ClassicHeartbeat.com __________________ On-line catolog Classic Heartbeat Pickup Parts WEHEPP@comcast.net Call us Toll Free (888) 338-2502 Like Us on Facebook No appointment necessary. 72 BB Chevy Custom Deluxe / Custom Camper 67 I-6 (Soon to be 5.7 LS1) Panel 68 BB Chevy Short Bed 72 6.0 LQ9 Short Bed Chevy 4X4 Olympia's fastest growing truck parts supplier. Olympia's home for Wayward Chevys

03-06-2003, 06:23 PM	#9
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	OK.....I have 3 sets of bolt holes on the frame of my longhorn for the auto trans crossmember. As far as I know(i could be off on this), the longhorns only came with either a 400 turbo , or a 4spd. the 4 spd did not have a crossmember under the trans(bell mount). My 383 is mounted in I 6 position, & uses the rear set of holes(short tail 400 turbo, just like factory). If you use the front set of holes , you are V8 SB position(factory position & stands). There are 3 1/2 " difference from fact V8 SB, & I 6 position. I havent done a BB swap(not Chev anyway), but assume that the other set of holes are for the BB(SB ,foward holes......I6 rear holes,& BB in between).......my thoughts are that the BB is set back from SB location(a couple inches), to help with the extra lenght on the nose. The measure from the eng mount, to the bell is the same distance on the SB as it is on the BB, so you should be able to use any of the sets of holes to mount(provided that the parts clear the firewall. To the best of my knowledge, this info is correct....... crazyL

03-08-2003, 12:56 PM	#10
casey Registered User Join Date: Jan 2003 Location: Kelowna B.C. Canada Posts: 2,048	That sounds like a hole lot of lovin going on Couldn't help it sorry lol Last edited by casey; 03-09-2003 at 03:09 AM.



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