98 Shortbox / 454 & TH400

[Short468]

Looking to try get some information on swapping a Big Block Chevrolet into a short box regular cab.

My main thing I am trying to find is the part number for the cross member when swapping the 454 and Th400 in. Also if anyone has the part number for solid motor mounts for this truck as well that would be great. Making a build list at the moment.



Completely abandoning the stock 4.3 V6

 

[someotherguy]

Trans crossmember part #? Who knows... but early early GMT400's, like 88-90 were available with the TH400 (3L80)...so that would be a start to looking one up. 91 was first year for 4L80E so previous HD auto trans were TH400.

Richard

 

[Short468]

Trans crossmember part #? Who knows... but early early GMT400's, like 88-90 were available with the TH400 (3L80)...so that would be a start to looking one up. 91 was first year for 4L80E so previous HD auto trans were TH400.

Richard

They don't make an aftermarket crossmember? Someone has to have / make one, I cannot find anything online. The question is asked but everyone keeps giving another option which I don't want. Already got the Big block and transmission built.

Not looking for OEM ones that come with the 454SS I can get that number in a few seconds

 

[someotherguy]

It was a suggestion to help you find one in the boneyard; you don't need one from a 454SS. If you want aftermarket then you have a world of online shopping at your fingertips.

Richard

 

[Short468]

I don't want the factory crossmember, Looking for aftermarket. I am searching all over online and cant seem to find it. Summit Racing, Jegs, BMR. Thought it would be simple to find but its not.

Had better luck finding the headers to fit the swap took me 5 minutes for those.

 

[89GMCJOHN]

Short - couldnt you relocate a stock 700r4 crossmember and in the worst case have to redrill and move to fit the 400 dimensions and get a new 400 transmission mount / pad ?

 

[Short468]

Short - couldnt you relocate a stock 700r4 crossmember and in the worst case have to redrill and move to fit the 400 dimensions and get a new 400 transmission mount / pad ?

Probably could but if I do that I would just go to a local fabricator and get one made. Id like it to be nice and clean without a big bulky piece. Or buy a universal DYI kit and make it work.

 

[1989GMCSIERRA]

There is very little reason for the aftermarket to make a crossmember that is already available from the factory on a stock chassis. usually aftermarket or custom cross members are made for a kit or some popular engine trans combo swap into a factory chassis like 6.0 powertrain on a gmt 400 swap.

you’ll most likely have a few options
1. Just do the easy one and find a GMT400 that came with a 400 trans. This would usually be 3/4 or 1 ton series. and this would be your cheaper 100% it will fit option. There are extra sets of holes o the frame where the transmission cross member is so you may be able to just unbolt your existing cross member and move it to the next set of bots and it would work.

2. Custom made cross member. No idea why you would bother doing that if a cheaper factory option is available.

3. diy cut weld and then have something powder coated.

 

[randy1965]

Using stock crossmember in stock location but notched for dual exhaust. Truck originally had 5.7/ 5 speed manual now a 496/th400 combo

 

[Schurkey]

Also if anyone has the part number for solid motor mounts for this truck as well that would be great.

Why on Earth would you take out the wonderful clamshell-design engine mounts and shove in "solid" mounts?

The whole point of "solid" mounts was that the older, non-clamshell mounts would separate from age or hard use, and the engine would lift under torque. Clamshells don't do that. There's ZERO need for "solid" mounts.

The O-N-L-Y problem with clamshells is not the design, but the ****** aftermarket replacement parts. Thin steel shells, made in China. "Good" original GM mounts are excellent.