Transmission

So I Have A 1989 1500 350/700r4 (rebuilt 3 Yrs Ago) That I Was Pulling A Boat Down Highway With. Got A Little Hotter Than Norm (maybe 10 Degrees) So I Pulled Over, Everything Seemed Ok. Shut It Down And Waited 10 Minutes. Started Back Up And It Dumped Trans Fluid All Out. Towed Hm, Took Out Trans, Front Seal Was Pushed Out A Little. Put New One In And Problem Solved, For About 5 Miles, Then Dumps Out Fluid Again. Why? Someone Told Me There Was Service Bulletin Out Sometime Ago About Them Having To Much Pressure And The Fix Was To Drill A Hole In The Valve Body And Put Some Retaining Clip On To Hold Seal In. If Thats The Case I Would Thought The Trans Shop Would Have Done That. (no Clip Found, Not Sure About Hole, Ran Fine For 3 Yrs) Someone Else Said Cracked Pump. This Is The Last Time For Me To R/R Trans (i Hope) So Any Ideas To Help Me Make It The Last Time Would Be Appreciated. Thanks

If it is getting hot and pushing out seal and a high mileage transmission it is time to rebuild it.
You have internnal slippage causing it to heat up.

Yes there is a tsb on drilling out pump but it is to late for that to help now.
But if you rebuild it and do not replace pump check it for needing the drill out.
Also they make a seal retaing clip to help hold front seal in.
To late now but.
It should have had on installed on it.

Here is a tough & weird situation. My husband just got a 1988 Chevy 1500 350 5 litre 8 cy automatice 4x4. Bringing it home it started backfiring and having difficulty shifting. He has done a complete tune up,checked all fluids changed all filters etc. After finishing he went to back up and lost the ability shift it back into anything. It is stuck in reverse but will still start-weird. He heard about the vacuume hose issues so he changed that, hopefully correctly because when he went to do it he noticed part of the hose wasn't even there that connected to the tranny.
So the questions are; why is it starting in reverse? How does he know if he connected the vacuume hose correctly? Is there anything else that should be tried before replacing the tranny?