Chevy & GMC Vans

I have owned my 88 Astro Van for 7yrs. It has had the tailshaft seal replaced 3 times as a result of leakage(the last time about 1 1/2 yrs ago). I asked my mechanic to change the front u-joint in case it was causing a wobble. Did not replace the back because he said it was ok. They changed the seal, a"joint" inside the housing and an o-ring. Now it is leaking again. Could the back u-joint(which has no symptoms of failure) be causing a wobble? Could a new tailshaft housing be the solution? Would I have symptoms(vibration) if the driveshaft was out of balance?
Unfortunately, I am unable to fix it myself, other wise I would keep putting in a new seal. The car is driven mostly locally and seldom on the highway. I have driven it 20,000 miles in the last 7yrs. Any Ideas would be appreciated. Thanks in advance.

If you replace the extension housing bushing, seal, and driveshaft yoke your problem will be fixed.

Smiliesafari wrote:If you replace the extension housing bushing, seal, and driveshaft yoke your problem will be fixed.

Thanks for the reply. Yes, the bushing(which I erroneously called a joint) and the seal were replaced on several occasions. The yoke was the only thing that was not replaced in the previous repairs. The seal and bushing repair held for usually a year or two, then the same old leak reappeared. It is probably the original yoke with the van. Thanks again, Smiliesafari.

Make sure there isn't fluid coming out the tiny hole in the end of the yoke itself. I remember Lockdoc (I think) had a small leak and found the yoke had a tiny hole. RTV'd it and no more issues.