tranny

Hi guys, I recently made an transmission oil change and replaced the shift solenoids, for some reason the truck drives but don't shift. Reverse 1,2,3 works. I was getting the code p0787 before and is still there even after replacing them. I went to autoparts to buy the solenoids, They told me...

I've been taking care of keeping the fluids changed with full synthetic penzoil but Im concerned. My 100K mile 2009 alpha is almost 10yrs old, is my daily driver and I have been doing a lot of towing lately. I have made 3 summer time round trips of 3400 miles pulling anywhere from 8K to 3500lbs...