Thread: TH400/208 Installation Issue

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Originally Posted by robot

On GM 4wd trucks of this era, the support is provided by the adapter. There is no location on the transmission for a mount since there is no tail housing.

I know the transmission is supported by the adapter plate, but what you're saying, is there isn't a trans mount that goes inbetween the adapter plate and the crossmember? I always thought there was...
I know it's different from the 2wd trucks, the crossmember is almost flat and bolts right to the tailshaft. I've done plenty of 2wd trucks. Maybe thats whats throwing me off so much, is that the 2wd, there is nothing that sticks down below the frame, whereas I swear I got 8 inches or more of stuff sticking down under my frame with this 4wd.

When dealing with different transmissions that didn't come in a 4x4 you have to make thing's work, I have seen some with the same problem you are having. Some as only one drop on the cross member and that's the ones that go with a 400 trans and it's on the passenger side and some have to put spacers between the crossmember and the frame to get the trans mount to work. The ones i've dealt with the trans mount bolts to the adapter between the trans and the transfercase. If it all didn't come from the factory that way you'll have to just make it work.

I looked at a few trucks that had 400 trannies in them, and the crossmembers are different, at least on those trucks. The crossmember that I have seems to be from a 700r4, which was probably what trans came in that truck in the first place.

I'll probably try to round up the right crossmember. On every truck I found with a th400, the crossmember dipped down about an inch at each side, then went straight across, instead of the W shaped crossmember I have been using. The trans mount is not as high (they are 2 "U" shaped pieces of rubber), and I get better ground clearance with the flat crossmember. Seems like it should work fine.

Originally Posted by streak

When dealing with different transmissions that didn't come in a 4x4 you have to make thing's work,

My transmission is for a 4x4. Always has been. Truck has always been a 4x4, too! Just different transmissions...

Thanks for the help!