Overdrive trans. In 51 pkp.

The 1949-50 Mercury overdrive transmission is the easiest bolt up with the least modification needed. You will have a side cover shift (requiring a steering column shifter) and you'll have to have a new driveshaft made up due to the shorter length. They use the same u-joint slip yoke. Same clutch, same clutch release linkage, etc.
 
It's mostly about fit and clutch actuation. The 49 to very early 51 Mercury type bolts right up as Mac VP mentioned with the same 1 3/8" 10-spline input. The only easy bolt up for the narrow mount 1-inch 10-spline transmissions such as used on Ford cars & later 51 thru 53 Mercury cars is all about the bell housing and clutch use. The only bell housing that will easily let that happen is the later 1951 Mercury cast iron bell but the clutch disc for the late 51 thru 53 Mercury would have to be used with the late 51 Merc throw out bearing. These housings are getting harder to find now days since they were only used during one model year and only part of that year to boot. The equalizer shaft for the late 51 Merc bell may also have to be modified to work but I don't know for sure.
 
Put a '49 Merc OD in a '48 F1 many years ago. Bolted right up. Biggest hassles were the side shifter on the trans and drive shaft length. Also don't forget rear end ratios. If you try to use the early Ford trannies you will have a bell housing issue.
 
50 Mercury , the Crossmember is going to need cut. And a new mount made for the tailshaft mount. I had one in a 40 ford pickup with column shift and it was a lot more work to fit then a F1. Use a 51 52 column shift column
 
sunshine said:
What trans. Will work . Will car trans. Work.? Sunshine
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This is a 49 Merc O/D transmission in my 1940 Tonner. I fabricated a new bracket to support the transmission and bolted it to the existing cross member and had a new driveshaft made to fit. That was the extent of the chassis mods. It was a straight bolt in clutch and all. We modified an early Ford 4 Speed shift tower to do the actual shifting chores. As has been suggested you will need to locate a column shift to complete the modification. I suggest you also consider the use of a T5 transmission. Do a search here on the site and there will be many threads on that topic. Good luck...
 

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expavr said:
This is a 49 Merc O/D transmission in my 1940 Tonner. I fabricated a new bracket to support the transmission and bolted it to the existing cross member and had a new driveshaft made to fit. That was the extent of the chassis mods. It was a straight bolt in clutch and all. We modified an early Ford 4 Speed shift tower to do the actual shifting chores. As has been suggested you will need to locate a column shift to complete the modification. I suggest you also consider the use of a T5 transmission. Do a search here on the site and there will be many threads on that topic. Good luck...
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Yours is the first I've seen that was able to get clearance at the solenoid in an F-1. The OD trans needs more of the crossmember cut out than a T5 because of that. The trans may "just bolt up" to the BH but that's the least of the problems. The OD is also a Car small input shaft so some clutch mods are needed (new disc at least).

A '51 F-1 pickup should already be side-shift, unless it came with the HD 3-sp or the spur gear 4-sp. If the truck is an F-2 or F-3, there is a chance the OD will clear the different crossmember used on those. More info would help.
 
Personally, I think I would go with a later transmission, like a T5 or that BW 4 speed used in some of the early 80s Ford pickups (3+O/D), or the cast iron top loader. Those early overdrives are pretty weak and certain parts are unobtainium. Anything R9 or smaller is weak and the R10 didn't come until mid 50s. The R-11 is best, later 50s until the demise of 3 speed overdrive around 1972.
 
After looking at all the overdrive options available now I decided on the T5. Glad I did.
The rear cross member is going to have to be modified either way. Drive shaft was easy. The Cornhuskers' kit made it a bolt in. The early S10 transmission I used was 20% OD. Worked perfect with the original 3.78 rear end.
 
Since you already have an open driveshaft to start with in the pick-up, a Borg-Warner T5 is just about a "no brainer". They are compact, plenty stout to stand-up to flathead power and more, and you can't find a sweeter-shifting transmission anywhere. By carefully choosing the correct model of the MANY available T5 gear sets, you can tailor the gear ratios essentially to perfection. A really prime, yet simple choice would be a 1983-'87 Camaro V8 T5 with a 2.95 1st gear ratio, as the 2.95 is extremely close to the stock old Ford 3-speed's 1st gear ratio of 2.82. You certainly don't want to end-up with one of the 4-cylinder or 6-cylinder T5s with a 4.03 1st gear, or even a 3.76 1st gear, which is essentially useless for a street-driven vehicle. To the suggested Camaro trans above, substitute an S-10 tailshaft housing which moves the shifter about 9-1/4" farther forward, to more-nearly replicate the old Ford 3-speed shifter location. Click on the link below for complete detailed article on this simple, bolt-on swap. This trans is shown below after the simple swap. This is a sweet deal! DD

http://lugnutz65chevystepside.weebly.com/a-camaro-t5-with-the-s10-conversion.html

A simple one piece trans adapter for Chevy to flathead is available from several sources, such as Wilcap, Speedway Motors, Offy and others.

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