2nd try, *&^^&* computer!!!
the 8LL is basically a 15 speed, but instead of an "up, over, and down" from 3rd to 4th, it's and "up, over, and up" it drives like a normal 10 speed, but has the deep reduction (and a blue splitter button on the shifter head)
you need to verify the EXACT tranny model number, just because it has more or fewer gears has nothing to do with the torque rating of the case and gearset
ie RTLO16918B is an 18 speed 1650ft lb rated tranny. push the engine settings, you'll junk it.
RTLO18913 is "only" a 13 speed, but this is rated for 1850ft lbs.
the dream tranny for you might be a RTLO20918, now you've got a 2050 rating, you'll see alot of these behind C16 cats.
there is nothing wrong with an 8LL, and it might be better for you, it will have the deep reduction gearing to let you get a super heavy load moving on a hill.
you will need to be careful, these build alot of torque at the differentials and axles. most of the broken power dividers, diffs, and snapped axles were in end dumps, in deep reduction. and, REMEMBER, if you have locking diffs, and you get stuck, ALL the torque will be pushed into the wheels that have traction. "POP GOES THE AXLE SHAFT!!!"
also, the lower (4.56 vs 3.73) the axle gears, the more teeth there have to be on the ring gear, so the weaker it gets.
that's why planetary drive hub type axles are found in heavy trucks and construction equipment. the final torque is made thru the reduction gearing IN THE HUB, so the driveline doesn't take so much stress and flex in long tubes or shafts.
see your nearest dealer, get a brochure from eaton/road ranger. it will give you the gear ratios and torque ratings for eack tranny, and you can decide what you need. look at the % chart for rpm drop for each gear step, it shows how close the gearing is.
i've run heavy wreckers for the last 11 years. i've towed in hundreds of broken trucks, and been involved in spec'ing new trucks, and repairing/upgrading the older ones. i've been over the continental divide in colorado at 134,000+ gross, towing an oversize truck and trailer. i'm no expert, but i've asked alot of questions and tried to learn from others problems!
99 F350 CC DRW 4x4 PSD 6 spd 4:10 Programmed, 4"exh, 8" lift Kelderman 4 link air ride rear, southbend clutch (and arm!) 295/85R22.5's, AFE stgII gauges, push bar, 07 lights, recon smoked fender and rears, ARE shell, DynaTrak combo front,
, Short throw Shifter, Airdog, Regulated Return fuel, Coolant filter, Bypass Oil Filter. Next:BB Turbo, CAC, Injectors, HPOP, Head studs, and anything else I can afford
Last edited by Colotow; 02-20-2008 at 12:58 PM.