couple trans questions

How can I tell what trans I have and are there Slant 6 trans that will bolt to a small block.

Also last summer before I got the car my dad had the trans worked on( pretty much rebuilt) but it has been leaking some every since and my dad was to stubborn to take it back because he felt the guy should have came and picked it up on his flat bed.

So I got it home and while I was taking all the e-brake cables off I looked around and did not seem to be coming from the pan or tail shaft or the lines or at that time any visible areas. so I cleaned at all up under there and filled it up and drove it about 150 miles with no real signs of leaking.

I have had it on the garage last few days cause the weather was terrible and I have been working on the carb and when I went out there today there seemed to be a puddle of fluid under the car. It seems to be coming from drivers side in the area of the shifter or there is a big fitting of some sort with wires and seems to be for reverse or something like that.

it seemed wet in this area so is it possible to leak from around where the shifter goes in the trans or is there any areas that seem to be an issue over there on that side of the trans


So I have cleaned that area up in hopes to get a better idea of exactly where its coming from

Thanks in advance