HIGH gears.....
I have 2.73's in my 81 van--it had 3.08's originally,but the diff case wore out where the side gear goes thru,and the 2.73 ratio rear end was free,so I put it in--the van had a 250 camelhumper 6 in it at first,then I swapped in an even more anemic 73-307 V8--I thought it was a dog with the 3.08's--the 2.73's are even worse, I thought it would not make much difference,but you can feel the power loss even though its not that much higher a ratio--
It does ok with the TH350 lockup tranny in it,its just not a ball of fire upon takeoff-- it does get good gas mileage on the open road--but climbing hills in VT and NH were a challenge,had to downshift into 2nd gear quite often(it will go 75 in 2nd gear before upshifting to 3rd by itself,not even winding out that high!)--looking back I wish I'd have bought the axle in another junkyard van that had 3.42 gears--its pretty rare to see anything lower than 3.08 in a G10 van here--I think the 307 would like being revved up higher,its short stroke makes it a poor lugging motor.
Your truck must be hard to get moving from a stop,as you said the clutch will be getting a beating if you have to ride it a lot on takeoff--I know of one C10 my friend bought from the phone company,it had a 250-6,a five speed manual tranny,(the crappy monza type tranny)and 2.56 rear end gears--it was all you could do to get it to take off on a hill,and the clutch would smell like it was burning all the time!--we put in a 350/TH350 from another parts truck--it was much better,the motor had no problem pulling that high gear,and it got good gas mileage--it might not have been an ideal gear for towing heavy loads or trailers,but he just used it for transportation anyway..
If you put a 14 bolt in it,are you going to change the front spindles so 8 lug wheels fit all around (I'm assuming your truck is a C10?)--I thought you could just swap the spindles,but the guy at the boneyard claims the ball joints and A-frames are different too,and you have to swap everything--others have said you can put 8 lug rotors on the 1/2 ton spindles by juggling the wheel bearing races and cups with different I.D's in them to "adapt" them--I looked into putting 3/4 ton suspension in my C10 when I thought I might put the caddy 500 motor I have in it,but decided it was too big an undertaking for me at this time-and I never got the "answers" as far as making the front 8 lugs to match the rear..
