I have a 93 bronco with 5.8 windsor and the e40d tranny,,,when im cruising and my truck goes to downshift when climbing a hill it seems to make a thump sound like i hit a bump or something ,,,,almose like a grinding noise,,,not really that bad but enough that you can feel it like its missing some teeth,,,maybe the gears are slipping,,,,need some help,,,what could this possibly be,,, i have no problems when i accelerate just when the truck downshifts,,,,any advice would be greatly appreciated,,,,thanks ,,,,,

 

I also have a 93 with the same motor and trans and am on this site trying to find out what rearends i can easily bolt in place of the 8.8. i tanked my second one yesterday and am very familiar with your problem. dont waist you time or money on the 8.8 go to a 9" out of a 78-85 bronco. this will require very little fab work and most of them have 3:50 ratio which can work with the 3:54 in your dana 44 front end

 

I would check the driveshaft out first. I know my 94 has worn slipsplines that make noise. I have also heard of E4OD's that start shifting rough when they need service. How many miles do you have on your truck and when was the last time you had your trans serviced?
Tim what are you doing to your 8.8's to make them fail.I have owned 3 trucks with them and never had a problem.I have used them with oversize tires and for towing my boat on a regular basis(I should really have a 3/4 ton)