Driveshafts for sure. Transmission cross member will likely be in a different set of holes. Trans tunnel cover will need to be modified for different shifter locations. Maybe a few other minor things that I'm not thinking of.

Should be pretty straight forward.

 

If your t176 has the same shifter as my 1983, you'll need to trim your tub opening and get (or make) a trans tunnel cover. I replaced my tub with an aftermarket one and it had the tunnel opening precut for the t150 and other transmissions that we more centered. Here are some pics of where I needed to trim. Good luck with the swap!

 

I sure appreciate this info.
I’m trying to look at everything that’ll be needed for an easy swap.
Thanks

 

Why are you making this swap? Old stuff busted? Or you want a 4 speed? The T150 isn't a bad transmission, and everything else is the same.

 

The main bearings in my 258 are going out. Plus 2nd gear is almost out in the t150 😉