727 help

honestly, I'd check the fluid level. remember that it needs to be in neutral to get a proper reading.

the whole "it had a different motor in it" is kind of cryptic. care to expand upon that?
He just got the car it had a 340 in it and I had just rebuilt a new 340 and he just swapped that engine out for mine the transmission ran good with the old 340 and it ran good with my new 340 then we changed the transmission fluid and noticed that the differential was really low on oil it has a pinion seal leak we just got a new pinion seal to go in it haven't done it yet