Leak from rear of transmission. Pan Gasket?

[Steve190E 2.3]

My 1988 300E has a leak that is quite possibly from the tranny pan gasket. I had the tranny out to replace the front pump seals, and at that time I removed the pan to replace the filter. I had just put the used tranny in about a week before and found that there was a leak around the front pump. I also noticed that there was a leak near the rear of the transmission. I checked the gasket which was brandnew when I replaced the tranny and it looked perfect. I finished putting it all back together and it is still leaking. How can I find out exactly where it is coming from? Also, if the pan gasket looks fine, how could it leak? Is it possible that the pan is bent and not sealing even though it looks perfect? Sorry about all the questions. BTW I don't know what I would do without this site.

[JDUB]

Sometimes the pans get bent or warped, from road debris or improper torque of the pan bolts. Clean the trans thoroughly and see if you can see where the leak is without driving it. The trans oil gets blown toward the rear of the trans. If it has been determined that the pans is leaking, check sealing surface of the pan with a straightedge to see if its the pan. Also check the sealing surface on the trans itself. Good luck.

[MikeTangas]

Don't know if this applies to yours or not...

On mine the pan was leaking. When I did the filter change I discovered that there were three short bolts and one long bolt, each with a set of "wings" to spread the pressure evenly. When I pulled the bolts, I notice the left rear bolt had the "wing" caddywompus across the corner lips instead of flush against the pan. The last person to change the filter didn't pay attention to where the bolts came from and obviously couldn't get one to tighten down so he improvised. On mine the long bolt goes at the right front corner.

Being bolted in incorrectly, plus the seal being pinched at that corner, was causing a small, but messy leak.