Battery : Good (replaced 2 days ago)
Alternator : Good
Starter: Good (replaced 3 weeks ago)

The car also slips 30mph-45 mph and the car does not move a inch even when in drive gear.

First time it happened and still wont start

Wasn't in the estimate section, did a quick search to no avail. Have a 1994 SS Impala with over 185K miles. Been extremely well taken care of, but have a head gasket starting to go. My mechanic isn't keen on replacing just the gaskets on such a high mileage engine. That make sense? Also, what would the difference in cost (labor more than anything) from a crate engine to a non-crate engine? I appreciate the assistance.

i have a chevy engine how do i tell what size the engine is 283 or 350 or 454 or 327 do the engine have marking to tell you what size the engine is