Front Axle Slipping Out of Transmission/Fluid Leak on 1993 Dodge Spirit?

[Sam]

I have a 1993 dodge spirit, front wheel drive, automatic transmission, v6 model with only 42xxx miles on it. Recently, I brought it to my mechanic to have a transmission fluid leak fixed. The mechanic said the fluid was leaking because the trans axle was slipping out of the transmission. He thought the "C clip" (something that clips the axle to the transmission, 1 on the inside of the tranny and one on the outside) on the trans axle may have been worn out and that was what was causing the axle to slip and hence causing the tranny to leak. He replaced the front transaxle and the car is still leaking transmission fluid (It's a slow leak; not huge, has been all along though.) He believes the C clip on the inside of the transmission may be the problem but said that I'd have to take it to a tranny shop and that the repair would cost thousands. Apparently, the transaxle has fallen out of the transmission again. Any ideas on how to fix it? Anyone else have a similar problem? Anyone know what C clip he is talking about? How long would my car last if I kept topping off the tranny fluid on a regular basis? He said the leak will probably get worse over time. I didn't ask him if it was a seal, but could it be just a seal or too much tranny fluid causing the axle to slip out? Any other ideas on an alternative problem that it could be?