Is it the original engine?

[Trip59]

How do you tell? I just bought a 72 GMC, the owner said it WAS a standard, now has a TH350 and a tilt automatic column (in my list of things to replace) but I don't know about the motor. The emissions sticker on the fender well lists a 307 with 2bbl carb, from looking at the motor, the exhaust looks appropriate (from memory) and it does have a 2bbl carb. The number off the pass. side pad has a TDA suffix, which is either a 72 307 or an 80 350.

What other numbers do I need and where can I find them, or can I ever really tell if it's the original motor?

It's a half ton with leaf springs in the rear, discs in the front, listed 307 motor, what tranny would it have had (so I may start hunting). Looks to have a low tunnel cab, and was column shift, does that limit it to a 3 speed?

I was also wondering about how to tell what the rear end was, guess I might as well lump that into this post.

If this belongs elsewhere, please accept a n00b's apologies.

Trip