Engine Crossmember Bolt Holes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mcmlxix · 07-17-2003, 09:05 AM

I have a 70 K5 4x4 blazer. I am swaping from manual to auto and was thinking of using the forward two holes and move the engine crossmember up. 1. for clearance issues for HEI and 2. for the length of the auto trans and x-fer. Does any one know what the two forward holes are for? Anyone using them? If so, what motor and trans are you running?

**CPNE** · 07-17-2003, 10:02 AM

If you're using the correct replacement th350/np205 combo, the overall length from bellhousing to rear driveshaft yolk should be the same as the 4 speed equipped unit alreay in there. The difference in length is made up by the adapter between the tranny and xfer case. You should not need to make any changes in engine/tranny placement or driveshft lengths.

I've done an HEI in a 72 4x4 and the GM HEI will fit albiet tight. If the firewall clearance on your rig won't allow it, then perhaps your cab mounts are in need of replacement.

mcmlxix · 07-17-2003, 10:13 AM

Actually I have an 88K5 donor truck with 350/700r4/NP208 so thats what I am worried about. I also planned on replacing the body mounts. I am one weekend away from pulling the body off to clean and paint the chassis. I will do the swap then so I have access to everything. If I decide to I might add a 2" body lift. Then I will have the clearance for the HEI but I am still worried about the lenght of the new drive train.

**CPNE** · 07-17-2003, 10:20 AM

I see your dilemma. Yukon Jack may have some insight as he has or does have his 4x4 down to the frame for a BB install

07-17-2003, 09:05 AM	#1
mcmlxix Collector of Projects Join Date: Apr 2003 Location: Las Vegas Posts: 3,106	Engine Crossmember Bolt Holes I have a 70 K5 4x4 blazer. I am swaping from manual to auto and was thinking of using the forward two holes and move the engine crossmember up. 1. for clearance issues for HEI and 2. for the length of the auto trans and x-fer. Does any one know what the two forward holes are for? Anyone using them? If so, what motor and trans are you running? __________________ Rich 1972 K5 Blazer CST Click HERE D60 BIG BRAKE UPGRADE Click HERE

07-17-2003, 10:02 AM	#2
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	If you're using the correct replacement th350/np205 combo, the overall length from bellhousing to rear driveshaft yolk should be the same as the 4 speed equipped unit alreay in there. The difference in length is made up by the adapter between the tranny and xfer case. You should not need to make any changes in engine/tranny placement or driveshft lengths. I've done an HEI in a 72 4x4 and the GM HEI will fit albiet tight. If the firewall clearance on your rig won't allow it, then perhaps your cab mounts are in need of replacement. __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

07-17-2003, 10:13 AM	#3
mcmlxix Collector of Projects Join Date: Apr 2003 Location: Las Vegas Posts: 3,106	Actually I have an 88K5 donor truck with 350/700r4/NP208 so thats what I am worried about. I also planned on replacing the body mounts. I am one weekend away from pulling the body off to clean and paint the chassis. I will do the swap then so I have access to everything. If I decide to I might add a 2" body lift. Then I will have the clearance for the HEI but I am still worried about the lenght of the new drive train. __________________ Rich 1972 K5 Blazer CST Click HERE D60 BIG BRAKE UPGRADE Click HERE

07-17-2003, 10:20 AM	#4
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,662	I see your dilemma. Yukon Jack may have some insight as he has or does have his 4x4 down to the frame for a BB install __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

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