Massive transmission fluid leak in car

[Lenovolost]

I have a 1984 300D Turbodiesel with 410,000 miles. I replaced the start soleonid last week, and within a day I noticed that I was leaking transmission fluid. I park this car on a clean concrete driveway, and it has NEVER leaked a drop of anything but A/C condensate before. In order to remove the starter, I had to losen the bolt that holds the dipstick near the top and move the dipstick/tube a few inches in order to get to the top bolt on the starter. I assume that I crushed the O-ring where the dipstick tube enters the transmission.

I really wasn't looking forward to spending my saturday under the car, so I called a local franchised transmission shop (I will refrAAin from nAAming them) to find out what they would charge for replacing the O-ring. They said $45 in labor and the cost of the part. Great! I just got my weekend back; so I thought.

I took the car to them and the owner took it for a drive then put it on the lift. He said that it was leaking from the front pump, the dipstick, and from the cooling lines!!! I asked how it was possible for all of these things to start leaking on the same day? He couldn't explain that one to me, but said that my tranmsission was worn out because it has 400k + miles on it. He said that it was shifting roughly due to low pressure because I was low on transmission fluid. (It has the typical shifting issues due to low vac pressure and a slipping band. Also, he must not have checked the trans fluid level because it was full.) He said that he would not repair just the O-ring due to liabilities!?!?!?

Anyway, I stopped by the local MB dealership and picked up a new O-ring ($6.95) and some new aluminum crushable washers ($3.00 ea)for the cooling line connection. It looks to me that It will be easier for me to get to where the dipstick tube enters the transmission, if I remove the cooling line. I guess I will go ahead and change the transmission filter and pan gasket while I am under there. Has anyone changed this O-ring before? Any advice?

Thanks.