70 firebird trans swap
 

Do i need to modify the tunnel to replace my stock trans with a 4l60e?

Sorry cant answer that... but curious why you want to put a 4l60e in a 70 bird unless it has a sbc or LS. If you want OD, a good 200r4 is a better option that will bolt right up to a pontiac engine.

It'll fit no problem. They're essentially the same size as a TH350/400, just slightly longer in the tail shaft.

I've got a 4L80E in one, no modifications.

I have a rebuilt 4L60 sitting under my bench for a long time, im building this car for a lady and i think the 4L60 will be a nice trans, Ames have a kit that modifies the original shifter and consol so you cant even tell, thats why.

Ok, just curious. Is this a sbc engine or Pontiac?