100% needs a new tranny. Opened it up and it was shot. I told him absolutely no Jasper. LOL.that's a not a good thing. that slow crank is basically like a dead short to the electrical system thru the starter. it's ******* the new starter too. in over simply terms, when there's a load like that, basically a short thru the none spinning starter, it steals all the electricity from everything else in the truck, the rest of the truck needs power to run during cranking, to run the ecm, fuel pump and injectors. these spikes and stuff in voltage is when these trucks freak out sometimes. the amount of posts that have been solved by replacing cables or tightening terminals is wild
my 2 cents would be load test the battery, directly on the battery posts, not the terminals. if it load tests good, replace both battery cables, make sure the new battery terminals are clean and tight. really tight, like you can't move them with 2 hands trying your hardest.
if it's still hard to turn over you have something mechanical, but it's probably just cables and stuff, unless you have a misery slow coolent loss too. cables are basically a maintenance item in these trucks. other vehicles they might be life time, these for some reason are not.
if you are handy with tools and want to test it. youtube voltage drop test and check while cranking.
you still probably need a tranny, because it seems 130k is a lot for a tranny these days.
The battery cables are a good tip and will investigate those when the truck comes home.