20 Questions (or less) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**hotrodmtodd** · 10-05-2006, 10:46 PM

I've been letting these build up.
1. Are automatic and 3-speed manual columns the same? My Cali truck was 3 on tree from factory. Looks like PO just put a PRNDL indicator on it and converted it to TH400. Is this POSSIBLE or did he more likely just swap columns?
2. I want to make my 72 Blazer 3 on tree, I have the CORRECT column from a 69. Can I do this swap fairly simply, or will it be a WIRING nightmare?
3. Thinking HARD about Big-blocking the 70 Burb 4X4 4-speed. Anybody want to talk me out of it, or give me advice on the BIGGEST obstacles to overcome? The thing really NEEDS to be BBC powered, if for NO other reason because of its sheer WEIGHT!
4. Can you use 73-up bellhousings with 72-back clutch forks?
5. I know that they are both EXTERNALLY balanced, but are SBC 400 & BBC454 flywheels REALLY interchangeable like I have always heard?
6. Is it the type of clutch, (ie: diaphram, Borg & Beck etc) or the type of fork
that dictates which throwout bearing to use? (long or short)
7. I hear a lot of talk about different truck 4-speeds (SM 420, SM465 etc) but how can I tell them apart? (visually) Some of mine have the reverse on the right, some on the left. I have noticed the ones on the left are GRANNYS. Do they take different PTO set-ups? Do the shifters swap out?

I better stop at 7 before I make anybodys head EXPLODE! Thanks, Mike

**Palf70Step** · 10-05-2006, 11:03 PM

1. No the columns are not the same, you'll need an auto matic column for the auto and 3 on the tree of the other.

2. Wiring is simple. I think the only thingh that is really different is the position of the neutral safety switch. or lack there of. Turn signal/Horn wiring plug the samer for both.

3. Talk to Yukon about big blocking a 4x4. he has gone through all that was needed.

4. That I dunno, I would say no...but not positive.

5, 6, & 7 I don't know enough about 4x4's and it has been way to long since I had a BB to remmeber.

Bob Moore · 10-06-2006, 01:23 AM

Mike #7 - go to www.novak-adapt.com Check out Knowledge Base and go to Transmissions. It details all the trannys you asked about. Very helpful site.

al's71gmc · 10-06-2006, 05:15 AM

Trans Q

Bob Moore · 10-06-2006, 01:52 PM

On the Novak site by clicking on the individual trannys you get a full rundown.

**hotrodmtodd** · 10-06-2006, 11:07 PM

Thank you Bob and Al. I printed those Novak pages for future reference. That was GREAT info, I learned a TON.
Bill: Thanks for your input. I sometimes wonder if I ask too hard of questions on here, because I don't get ANY answers occasionally. (I better get a crate motor and a slushbox I guess, huh?) Guess I will be "trial and erroring" a lot on these ones. I will try to contact Yukon for some insight. Take care, Mike

10-05-2006, 10:46 PM	#1
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 918	20 Questions (or less) I've been letting these build up. 1. Are automatic and 3-speed manual columns the same? My Cali truck was 3 on tree from factory. Looks like PO just put a PRNDL indicator on it and converted it to TH400. Is this POSSIBLE or did he more likely just swap columns? 2. I want to make my 72 Blazer 3 on tree, I have the CORRECT column from a 69. Can I do this swap fairly simply, or will it be a WIRING nightmare? 3. Thinking HARD about Big-blocking the 70 Burb 4X4 4-speed. Anybody want to talk me out of it, or give me advice on the BIGGEST obstacles to overcome? The thing really NEEDS to be BBC powered, if for NO other reason because of its sheer WEIGHT! 4. Can you use 73-up bellhousings with 72-back clutch forks? 5. I know that they are both EXTERNALLY balanced, but are SBC 400 & BBC454 flywheels REALLY interchangeable like I have always heard? 6. Is it the type of clutch, (ie: diaphram, Borg & Beck etc) or the type of fork that dictates which throwout bearing to use? (long or short) 7. I hear a lot of talk about different truck 4-speeds (SM 420, SM465 etc) but how can I tell them apart? (visually) Some of mine have the reverse on the right, some on the left. I have noticed the ones on the left are GRANNYS. Do they take different PTO set-ups? Do the shifters swap out? I better stop at 7 before I make anybodys head EXPLODE! Thanks, Mike __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner

10-05-2006, 11:03 PM	#2
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 46,818	Re: 20 Questions (or less) 1. No the columns are not the same, you'll need an auto matic column for the auto and 3 on the tree of the other. 2. Wiring is simple. I think the only thingh that is really different is the position of the neutral safety switch. or lack there of. Turn signal/Horn wiring plug the samer for both. 3. Talk to Yukon about big blocking a 4x4. he has gone through all that was needed. 4. That I dunno, I would say no...but not positive. 5, 6, & 7 I don't know enough about 4x4's and it has been way to long since I had a BB to remmeber. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

10-06-2006, 01:23 AM	#3
Bob Moore Registered User Join Date: Feb 2004 Location: Tacoma WA Posts: 1,365	Re: 20 Questions (or less) Mike #7 - go to www.novak-adapt.com Check out Knowledge Base and go to Transmissions. It details all the trannys you asked about. Very helpful site. __________________ 67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow

10-06-2006, 05:15 AM	#4
al's71gmc 4 eyed fever Join Date: Jul 2005 Location: Eureka, Nevada Posts: 500	Re: 20 Questions (or less) Trans Q Attached Images __________________ 1971 GMC 2500 4x4 1972 GMC Sierra Grande 1/2 t 4x4-#1 son's truck. Recently completed resto. 4 YO daughter," Daddy, I like your truck better than Mom's." (2000 F350-ranch truck) Smart kid!!

10-06-2006, 01:52 PM	#5
Bob Moore Registered User Join Date: Feb 2004 Location: Tacoma WA Posts: 1,365	Re: 20 Questions (or less) On the Novak site by clicking on the individual trannys you get a full rundown. __________________ 67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow

10-06-2006, 11:07 PM	#6
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 918	Re: 20 Questions (or less) Thank you Bob and Al. I printed those Novak pages for future reference. That was GREAT info, I learned a TON. Bill: Thanks for your input. I sometimes wonder if I ask too hard of questions on here, because I don't get ANY answers occasionally. (I better get a crate motor and a slushbox I guess, huh?) Guess I will be "trial and erroring" a lot on these ones. I will try to contact Yukon for some insight. Take care, Mike __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner



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