Thanks for the information Bob those two the mounts and wiring harness was holding me back especially the frame mounts. Yes it is a sprint zd engine runs great but no thrill to me will eventually sell it because I won't be putting it back in. I've had the car for awhile and earlier on I bought a couple 400's to install but never did. What happened is I never knew what a firebird sprint was and as time went by I learned about the ohc6 and was having second thoughts about degrading the originality of the car. But I ain't gettin any younger and don't want to start on another ride so I've decided to make the swap so I can enjoy it. You mentioned about the later engine and bolt holes. Years ago I bought a 79 400 pwh engine from a guy cheap he wanted to install it in his 65 gto but he couldn't bolt it in so I bought it also not knowing about the engine bolt holes or adapter plates. Thanks again I've got a few more parts to gather up then ill make the swap.