Leaking 904 Transmission.

We put it up on a rack and there's a vertical plate at the front of the transmission. We loosened the two bolts we could reach and some transmission fluid leaked out so I'm thinking the front seal is bad. I found a guy in St. Louis that works on these older transmissions. He wants $500-600 to replace all of the outer seals. He also talked about just rebuilding the transmission but at only 66K original miles I'm not sure it needs it. Anyone have any thoughts on the price to replace the seals and also the need for a rebuild? Thanks in advance.