Please help. I would like to swap out my 84 model 350 and replace it with a vortec 5.3 or 6.0. I can get a wiring harness from painless, but I was wondering if anyone knows were to get an adapter plate to mate the vortec 5.3 to a 700r-4 trans.

 

wow now that swap sounds cool have you checked with b&m they sell some adapters to mate transmissions to different engines...

 

Are you sure the vortec engines use a different bellhousing? They use a 4L60E or a 4L80E if think, and I'm pretty sure the bellhousings are the same as a Gen 1/2 SBC. I could be wrong though, it has happeend once or twice before.

 

I know the bellhousing has the same pattern but:

the LS family of motors uses a metric bolt to attach to the bellhousing, no problem there, just get them instead of the standard bolts.

they also only use partial number of mounting bolts. I believe the middle bolt(of the three) on the passenger side is not used becuase the cylinder is so close to the back of the block.

this is the biggest gotcha-I don't know if the crank centerlines are the same. You would need to find that out. If that doesn't check out, then you could just run an LS 4l60E, and let the LS ecm control the trans as well.

 

It takes a special bushing to put the torque converter in the right place. Don't try to tap the bolt hole that isn't there. You are assured to tap right into the number 8 cylinder.

 

No adapter plate is needed. The Gen III torque converter is needed however.

Leave out top right bolt and you're good.