Finally got the car all buttoned up and made it to a test n tune few weeks ago. A trans leak kept me from making multiple passes. Trying to zero in on this pesky leak and it appears it's coming from the gasket between the tail shaft housing and the case. Buddy says tail shaft can be pulled while trans is in the car and this gasket replaced. Any feedback from the group on things to watch out for on this before I tear into it? I assemble my own motors, everything on the car, but have never really dove much into transmissions. . .leave that to the guys that know. Any help, tips, pointers be much appreciated!

Before you blame the gasket, be sure the leak doesn't originate at the infamous rear band lever pin.

It's coming from this area to the left on the drivers side.

Yes, you can easily remove it in the car. Floorjack under the trans pan, remove the driveshaft, crossmember, and trans mount from the housing. Disconnect the speedometer cable, remove the speedo gear, remove the two screws holding the access plate under the trans mount to get to the snap ring. Remove the housing to case bolts...then expand the snap ring while sliding the housing off.

Clean the area real good with brake or carb clean and sprinkle baby powder on the rear cooler line fitting and gasket area.

Run it on the hoist or stands and see what’s leaking. I have seen a few cases cracked in this area from guys over torquing the rear cooler line fitting in the case, or not using two wrenches to tighten the rear cooler line.

Thanks guys, no speedo gear in it, it's plugged. Originally I thought it was the fittings at the rear line, replaced those and re-fired yesterday, seems it's coming from that gasket around and just left of the lower bolt. Had no leaks initally upon first fire of the car and backing in and out of the garage, went to track for first test and tune and with pressure on a run it developed the leak. After new fittings on the AN hose that area and the area around the fitting was dry, In my opinion the bolts from tail shaft housing to case were not very tight, and fluid leaked at the gasket, even snuggin them up it still dripped a small bit yesterday on a test fire. I've always felt like once trans fluid starts somewhere, the only way to seal it 100% is to fully clean and re-seal 100%. I will inspect the rear line tapped area again as well thanks!

I had Cope build a transmission , it leaked on the top two tailshaft bolts or I thought it was .. tunrs out , he stripped all the bolts out and instead of fixing it right , he blobbed on a bunch of silicone and stuff the bolts in .. hack

If you have to remove the tail, put the shifter in Park and turn the driveshaft until you feel it engage in park before you start the job...this will make it easier to remove and reinstall the housing.

Give the gasket a few coats of copper coat, it won’t come off and get in the trans, also check the depth of the case hole versus the bolt length. Torque 24 ft lb.

I personally silicon the tail housing bolts. Not an overwhelming amount, but just enough to cover a few threads. I have had two 727s apart recently that had loctite on the tail housing bolts to help any fluid get past the threads. I have also seen teflon tape or liquid teflon used to help seal the threads.

Agreed, this seemed to be where the leak started from. I used some ARP thread sealer on it, now seems to be coming from gasket. Someone else mentioned park rod could be tricky, not sure what I'm in for there. Rest seems somewhat easy. Thanks for all the tips and help, tonight is the night to dig into this one. I'lll post an update.

Its pretty straight forward...I've done it too many times... once with water running in my collar and out my pant leg

that happened to me once............ i missed my mouth with the beer can........ are you sure that didn't happen to you ? [just funnin' with ya ! ]

So before tearing it all down, I took the previous advise to coat with baby powder. Everything is fresh and brand new, so wiping down before was a breeze. So did that, applied a coat as best I could to the entire rear area. Ran the car in neutral for a bit, no leaks. Ran it again for a bit longer, no leaks. Ran it a 3rd time and finally got some heat starting and it leaked. Turns out it's coming out the vent tube which is just above the rear line port. Was still showing high on dipstick, so I took 2 quarts out. Then it no longer registered on the dipstick, and while running I added half a quart. Jumped in and came up on the converter in reverse (told this was the highest pressure) and leaked out the vent again. So, tomorrow going to try a factory dipstick and see if I can get an accurate fluid level. Have a locking aftermarket one in it. It doesn't leak a drip while sitting, so starting to rule out the gasket and I'm thinking fluid level is to high.

Do you have a pic of your vent location?

Angle somewhat skewed, under the car and at an angle. But had fluid come out the vent, case was wet below vent and above line port by touch. Red is vent, blue line is path fluid is taking.

Nope it was a parking lot in Reading PA... fortunately (depending on how you look at it) we got rained out so I had time to fix it...was laying under my race truck, under a street light during a rain storm. Thank goodness for youth!

Moving the vent was the dumbest thing I did to a 727 .....once. For the same reason here.

I never move them when I do one now.

Is the vent located in the case or tail housing?

I recently dealt with this with two 727s with that same plastic vent being in the tail housing. We fixed it by pulling the tail housing in the car, tapped the holes for 1/8” NPT, put a 1/8-3an male 90 degree fitting in the hole. Then attached a 3an hose to a catch can.

No longer leaks.