I bought a New/Remanufactured A518 RH OD Transmission fresh out of the box and installed it in my 1990 D350 1 ton base cab. She's a 360 LA ext balanced engine with the Dodge/Chrysler B & M flexplate.

Allow me to preface by typing that this is a project truck. So! I have registered the warranty, and done EVRY Meticulous step needed to reinstall the tranny. Plumbers tape on the brass fittings, and plumbers tape on the mating metal lines, new aftermarket 3 core radiator, plumbers tape on the brass fittings where the lines meet the radiator etc. I have not installed the driveshaft yoke. So while filling up the trans with new fluid, the OD tail shaft started leaking, at the very end where the new output shaft seal is. This might be a crazy question, but is it supposed to leak without the yoke installed on the splines? I kinda destroyed the UV joints in the removal process, but I'm kinda sweating this, because the transmission was $2k.
Hopefully, the yoke will solve it.

 

The short answer is yes! The longer answer is, the driveshaft inserts over the splines and the seal (SEALS) itself around the shaft. You began filling it before
the install was complete, that's all. You're good!!