I have a question on which engine mount to use. I purchased the car with a Chevy engine which has been removed and installing a Pontiac engine. The engine is from 73 Catalina. Could I use the Chevy mounts or do I find and install the original engine subframe mounts. Thanks for the help.

For Pontiac engine you'll need Pontiac mounts to attach it to the subframe. The chebby's won't work. Trans bellhousing is also different, and possible trans xmember changout may be needed as well to get the angle right. And likely driveshaft length will be wrong after you get it set in place. A lot will depend on whether or not the original Chevy conversion was done correctly in the first place, and whether you're pulled out a SBC or a BBC, and possibly the age of that motor you're pulling.

I just swapped a Chevy 350 out of my '69 and replaced it with a '74 Pontiac 400. Summit has the frame and motor mounts and I did not have to change the crossmember or the driveshaft length. I also swapped a Chevy TH350 for a BOP TH350 at the same time. There was a boss on the 400 motor that blocked the one motor mount from sitting flush, I had to remove some material from the motor mount and then everything fit perfectly.

Thanks for the replies and where to find what I need.