RUG SR-OD single rail 4 speed overdrive: 1978/83: misc 200/250/255/302 cars, F100/150 300/302 2WD & E100/150 300/302/351W

Cars & F100/150's: The shift lever fits into a flange located between the transmission and extension housing. The end of the lever fits into a nylon bushing that is notorious for cracking apart.

POS bushing is obsolete, available NOS and from Northwest Transmissions.

IMO, forget about the RUG, it's a "weak sister." Swap rear end gears instead, much cheaper plus the driveshaft won't have to be modified.

 

Yup.. early to mid-80s. It'll bolt up neatly to a six. My neighbor had one behind his six with over 300,000 miles with no rebuild on the engine or trans. He is meticulous with maintenance. Those transmissions have a big RPM drop off between 2nd and 3rd gear and some guys don't like it for that reason.

He sold off his 81 F100 and treated himself to a Chevy Silverado. Five months later a drunk floozey forgot to turn at the dog leg and took out his Silverado. He was thankful because he had grown to hate it.... went out and got an F150.

 

Toploader 'imposters' (OD version) are not stout. Just sayin'. They were primarily used in passenger cars like the Granada/Monarch as a cheap OD option. It's the step between gears that actually gets you on these trannies. That torque change can be disastrous under significant load.

 

Adding an over drive trans or add on tail shaft over drive unit is for the most part not cheap.

Unless you just happen to get lucky and find a setup at the junk yard. But many guys have an eye out for one an hit the J-Yards a few times a week on the hunt for such tranny's or a gear vendor plus other o/d units.

So, I'd say your best bang for your buck is cheapest is changing rear end gears or to taller rear tires.

Putting in a car tranny's would not get you very low stump pulling gear if you were to use your truck like a truck. And sometime sound great until you spend $1800-$3500 for that extra gear then later find your getting 1.5 or 2 mpg more at best.

Your best gas saving speeds is like 50-55 the way it came rolling off the assembly line.

Also learning to operate your truck with a tach & a vacuum meter will yield your best gas mileage as, I found having driven my truck over 30+yrs using these two types of meters especially when towing or hauling..

Orich

 

X2 everything orich just said.

 

Thanks for all the replies guys. I have a lot to ponder, but I'm warming up to the taller gear in the third member. I wanted to go to a taller tire as well so I may just be able to do this swap and be happy with my original 3-speed. I think it may be a Top loader - has an access panel right on the top of the gear box...

 

Thanks for summing it all up Orich!

 

There is no direct bolt up OD option for you except in 1977-78 ford made a toploader overdrive. It is basicly a 4sp, but 4th gear is an od. It will bolt to your existing bell housing, but needs a 4 speed floor shifter. Check out Top loader imposters & David Kee toploader transmissions

 

A Tremec TKO is a bolt-on if spec'ed with a shortened 10-spline input shaft.

 

Thanks for the info!

 

Stock bell housing and no adapter plate. Glory.

 

Thanks again. I looked up the specs. Nice tranny!

 

The choice is yours and the only other factor that dictates outside of that is your budget but, a simple rear end gear change means you have to be willing to give up something. --either on the low end or the high end.

If you go to a lower gear ratio (higher numerically), you'll have plenty of low end grunt but, the trade off is getting even less gas mileage and higher engine RPMs at highway speeds. An engine that's being spun faster, to maintain a given speed, is naturally going to wear out faster as well.

On the other side of that, simply swapping to higher (lower numerically) rear end gears will give better fuel mileage and lower highway RPMs but, it means you have to be willing to lose low end grunt and pulling ability, --if you ever plan to pull a loaded trailer.

An overdrive is likely to cost more than simply swapping out the 3rd member in the rear end however, an overdrive will allow you to keep a low set of rear end gears for low end grunt and pulling a trailer but, the rest of the time, you aren't being penalized on the highway with high engine RPMs. --you get the best of both worlds, with an overdrive, that a simple rear end gear change, alone, can't provide.

In many cases, a lower set of rear end gears (with an overdrive) can actually end up being even higher than a high set of rear end gears, without an overdrive.

I'll give you an example. Let's say you had 3.25 gears in the rear end. This isn't a low gear set but, let's say you feel that's too low and you want to go to an even higher gear set so, you swap to a set of 3.00:1 rear end gears.

Your mileage and cruising RPMs may be better but, acceleration is going to be reduced as will your trucks pulling ability.

Now let's say you had an overdrive transmission and a set of 3.70 rear gears. 3.70 is lower than 3.25 and much lower than 3.00:1.

Let's say the overdrive transmission has an overdrive ratio of .68:1. Final drive equivalent with an overdrive is figured by multiplying the transmissions overdrive ratio by the rear end ratio.

.68 x 3.70 = 2.52:1

In overdrive, with 3.70 rear end gears, the final drive equivalent would be as if you had 2.52:1 rear end gears, instead of actually having a 3.70 ratio.

In the end, with an overdrive, 2.52:1 is much higher than 3.00:1 and as I think you can see by the math, you wouldn't give up low end grunt, acceleration or the ability to pull loads. The other side is you'll burn less fuel at highway speeds and have an engine that's turning less RPMs than you would with just a change in rear end gears.

Opinions are as varied as the number of people who will respond to this thread and can be argued over 'til the cows come home. However, math is based on absolute facts, not opinions. I think you can see, in the end, what direction will gain you the most here.

 

but don't forget to factor in COST X TIME / MECHANICAL ABILITY but other than that ultraranger is spot on with how i see it

 

I had mentioned in my previous post that the budget would dictate the transmission that could be installed and that it would likely be more costly (on the front end) than a simple 3rd member/gear swap.

If the current transmission works, it can continue to be used while another transmission (overdrive), and all the related install parts are gathered. Once all the needed components are gathered, the transmissions can be swapped.

This would spread the cost out over time and not destroy the budget by trying to do it all at once. --it's the same thing I'm doing with my Ford 4R70W 4-spd automatic overdrive transmission.

I have most of the rebuild parts/tools to rebuild it. In the mean time, my stock C-4 gets the truck around until I can rebuild the 4R70W transmission that will replace the non-overdriven C-4. --by the way, I've never rebuilt an automatic transmission before.

A truck with no overdrive has to be geared to do one thing or the other; either it will be geared to pull heavy loads and will get poor mileage in the process or, it'll be geared to cruise at highway speeds, get decent mileage but will be greatly lacking in the ability to pull loads.

An overdrive transmission is the common denominator that will allow the truck to handle BOTH scenarios very well.