94 Chrysler transmission problems

I recently was driving about 50 mph and my trans suddenly went into neutral....but in about 10 seconds it went into the LEMP mode......I took it to a small transmission shop and he put it on the analysis machine and pulled codes.....he said it showed nothing on input....but on output it showed a hydraulic problem.....probly a pump or a cracked drum thats what usually happens....it has been vibrateing under a load going uphill for a couple of weeks.....you know like a tire with a bubble on iit....and there is a whine in the trans kind of like the old hydramatic when it was low on fluid.....but its not low....would I be smart to get another opinion as he never checked the fluid or even drove it........next quiestion is thissomething that I can replace myself I have and extensive mechanical background......I have found most parts on the internet already......any help would be appreciasted.........