Engine/Transmission compatibility

Let me first say that I am no more than a backyard mechanic hobbyist so if you are kind enough to give me feedback think of talking to a carrot or something else of that mechanical background. I have a 73 Charger with a 360 in it from some truck I believe. The previous owner cut the oil pan in half and welded it back together to make it fit. Not sure what model of transmission is in it and would like to know a couple things if I could:

1. Where would I find the plate or stamp that identifes what model transmission is in this car?

2. What size block would fit in here without too much modification such as new bell housing, new driveshaft etc.?

My hope is to go through craigslist or something similar and pick up a nice 400 or 440 that we can rebuild and stick in here. I find many adds that list an engine/transmission but am not sure what will or will not fit into this car.

Thanks for any assistance. Bought several books thus far but nothing seems to clearly lay it out for me.

Big block engines (440/400/383) will need a big block transmission to go with them, the bellhousings aren't the same. The engine swap will be pretty straight forward, with a change of the motor mounts, exhaust and drive shaft change or shortening. You will have to extend some of the wires for the big block, like the wires to the distributor. All in all, it's not too hard at all. If you find a sale with the engine/tranny together, you just fixed most of the problems of the swap. I'm sure there are a few threads on the forum about this swap, just do a search at the top, or if you're close to one of us, I betcha you could get someone to give you a hand off and on, at least to look at it and point to something and go "that's wrong, ya gotta..."

For the small block you have in the car now, the easiest way to tell what tranny you have is to look at the tranny oil pan: basically the 904 has almost a square oil pan on it, the 727 has a kick out to the side. it's a pretty obvious difference.

If the pan on your engine has been cut and put back together, I think you hit the nail on the head, that's prolly out of a truck (which has a pick up on the end) instead of a car (which has a pick up in the middle).

Perfect thank you very much for your time!