I have a 78 F-350 long wheelbase 351w 4 speed granny tranny. I would like to replace the tranny with a 6 speed double overdrive, or something that will allow me to drop my engine speed while on the highway.

anyone out there who knows transmissions and what would work best.

Currently the truck modifications include:
Chopped the frame to just behind the rear spring hangers
added air bag suspension
added a dumpbox (I haul up to 4000 lbs on occasion)
added 2 33 gal round fuel tanks (eliminated stock fuel tank)
added twin stacks just behind cab

would like to add:
engine driven air compressor
2 air seats
hydraulic 12,000 winch (mounted between frame rails behind cab)

 

DANG dude your haulin all that w/ a WINDSOR???

 

check out gearvenders for OD.
which 351w do you have, is it the stock motor to the truck, how many valve cover bolt does it have?

 

I have priced GearVendors they are priced very high especially when you take into account you will have to have driveline work done. I would like a syncronized 3 or 4 speed brownie w/2 overdrives (may have to get it modified to do such).

yes .... I haul all that with a stock Windsor. it has 3k miles on a new engine, stock 2bbl (built at a local carb shop.

 

long WB f350 with 16 or 16.5 rims, and you want to LOWER the 351w's highway RPMS with a overdrive? Somthing doesn't seem right to me.

 

oldhalftons,
What seems to be wrong with this thought? I presume that reducing RPM at highway speeds would help w better fuel mileage and possibly prolong engine life.

Please help me out here? What are your thoughts on the matter?

Padruig

 

windsers like to pull over 2000rpm and around 3000. you must be right in the sweet spot now and there is alot of weight in that truck.

I could see the overdrive if you had a m-series motor or a 460

 

ya I'd think w/ that much weight and that low gearing you'd prolly lose mileage because you'd have to have the throttle punched just to keep it rollin

 

If you can keep the carb out of the secondaries it will do OK to lower rpm's.

Like oldhalftons says, wheezers are not a torque motor, they get their HP from rpms.

You might want to look thru the posts in the 351W engine forum and also the trans diff and axle forum.

 

It is easy to keep the carb out of the secondaries..... it's a 2bbl motorcraft. I have access to a 460 (in my other truck 75 club cab camper special) I just don't know if I want to sacrifice the truck. I could put the 351 on the c6 in the 75 But I would have to do the whole "where do I get the bellhousing"thing.

 

Then you need to keep the power valve from activating. Unless of course you like the light feeling in the wallet.