4-speed trans. crossmember ?

[airdale94]

Is there a difference between a 4-speed trans. crossmember for a V-8 and a 6 cyl. ? Or are they the same. I have been trying to wrestle in a 6 cyl. one when I heard there was a difference. 68350 has one posted in the Parts For Sale (V-8), but it looks exactly like my 6 cyl. mount.

http://67-72chevytrucks.com/vboard/s...d.php?t=299166

Anyone no for sure?

[Shyguy]

We just put a l6 with a granny 4 speed in a frame that was setup originally for a V-8 with a 3 speed without a problem.

The cross-member that was in the frame was riveted in so I know it was original. The transmission does not attach to the cross-member, the bell housing does.

We did have to put the l6 engine in first and then mount the transmission on it from underneath.

I sure hope this helps.

Danny

[airdale94]

Did you use the crossmember that was in the truck originally?

[Lugnut64052]

They're the same.

I changed a '68 from an I-6/three-speed to a V-8/four-speed with no problems at all. An easy, no-problem, bolt-in swap.

Incidentally, that trans crossmember setup looks exactly like what GM used in their medium duty trucks (school buses, U-Haul trucks) for many years. Same bellhousing trans mount, same Z-bar/push rod setup, etc. Another testament as to why our trucks have lasted so well all these years and are still motivating down the road.

[airdale94]

I just went and tried again. There's no way my x-member is going in except in the 6 cyl. position. You can put a V-8 4-speed in the 6 cyl. position but it puts it up against the firewall.

[Green Machine]

The crossmembers for a manual tranny, with the bellhousing bolting to it, mount on different spots on the frame, depending on either I6 or V8. IIRC, because of the way the frame starts to curve in that area, the crossmembers are not interchangeable, they look very similar of course, but sounds like you need the correct donor xmember, rivits cut carefully and then bolt it in.

[Shyguy]

I guess we were lucky when we put the l6 in with the 4 speed transmission.

The previous owner said it was from a '69 and he thought it was from a truck that had a V-8 with a 3 speed. I am sure glad the previous owner was wrong because the engine and transmission fit perfectly.

Danny

[airdale94]

Originally Posted by Green Machine

The crossmembers for a manual tranny, with the bellhousing bolting to it, mount on different spots on the frame, depending on either I6 or V8. IIRC, because of the way the frame starts to curve in that area, the crossmembers are not interchangeable, they look very similar of course, but sounds like you need the correct donor xmember, rivits cut carefully and then bolt it in.

OK, Great Thanks! That makes the most sense. Hopefully I will be getting one soon. 68350 has one for me. Thanks again!

[Lugnut64052]

Originally Posted by Green Machine

The crossmembers for a manual tranny, with the bellhousing bolting to it, mount on different spots on the frame, depending on either I6 or V8. IIRC, because of the way the frame starts to curve in that area, the crossmembers are not interchangeable, they look very similar of course, but sounds like you need the correct donor xmember, rivits cut carefully and then bolt it in.

Interesting. The one I changed over went in so smoothly I figured they had to be the same. Everything worked, including the 4-speed driveshaft. The engine mounts ended up in the rear pair of frame holes.

Sorry if I disseminated some bad information.

[airdale94]

Originally Posted by Lugnut64052

Interesting. The one I changed over went in so smoothly I figured they had to be the same. Everything worked, including the 4-speed driveshaft. The engine mounts ended up in the rear pair of frame holes.

Sorry if I disseminated some bad information.

Hey no problem. I just wanted to get this strait. I started on this last fall including a frontend changeover, all I got done befor the cold was the frontend. Here it is the middle of summer and I'm chasing parts again.

[airdale94]

Originally Posted by Lugnut64052

The engine mounts ended up in the rear pair of frame holes.

Yes that is the 6 cyl. location. I tried this with mine, which will work. I just diddn't like the engine in that position.

[70rs/ss]

Yeah a v-8 will drop in using the 6 stuff, but it needs to be in the same location, so the SBC will be forward a bit. If you move it back you'll need to shorten the drive shaft as well, probably not a big deal but worth mentioning. Probably $75 or so at a driveline shop.