Done with my toploader... Now what???

Hello, first post here. My daily driver is a 1981 Ford F100 with a 300 series mated to the factory SROD manual gearbox. We stand out on the road here in California amongst the Teslas and Range Rovers.

We all know the SROD is not exactly the crown jewel of manual transmissions. Previous owner thrashed it pretty badly, my brother and I pulled it out and rebuilt it a couple years ago, but now it's jumping out of 2nd all the time, the ratios are terrible and I'd like to upgrade.

This is my daily driver and I don't have unlimited time or funds. I'd like to get back on the road as soon as possible. What options do I have for a gearbox that would be relatively accessible and would mesh with my motor with minimal complication? I am new to this. Please school me on my options.
 

bubba22349

Top Poster
Staff member
VIP
Supporter 2021
Supporter 2019
REDLINE 10K
That's one Great Looking 1981! I liked the 5 speed M5OD that was in my 1994 F150 with the EFI 4.9 / 300 Six it had a 3.08 Rear axle Gear too. Was a very good combo for a commuter truck got great MPG too, you should be able to find one in California fairly cheap at the local Pick A Part. Now if you are pulling trailers or wanting to haul a lot of weight then you might want to look for a ZF 5 speed. Best of luck
 
That's one Great Looking 1981! I liked the 5 speed M5OD that was in my 1994 F150 with the EFI 4.9 / 300 Six it had a 3.08 Rear axle Gear too. Was a very good combo for a commuter truck got great MPG too, you should be able to find one in California fairly cheap at the local Pick A Part. Now if you are pulling trailers or wanting to haul a lot of weight then you might want to look for a ZF 5 speed. Best of luck
Thank you for the reply. I'm assuming I'd need to source the correct bell housing or adapter for the M50D ?
 

bubba22349

Top Poster
Staff member
VIP
Supporter 2021
Supporter 2019
REDLINE 10K
If you hunt for one the M5OD-R2 this is the heavier duty version that were used behind the 4.9 Inline six (300) and some were also used behind the 5.0 V8's they are only found used behind the EFI engines from 1987 to 1996 in the F150 pick up's some were also used in the light duty F250's (under 8500 Lbs.). They will have an Integral Bell Housing so there would be no need in hunting for the correct Bell Housing. These Transmission's use a Hydraulic Clutch so you want to get that set up with the trans. They came in both 2 Wheel and 4 Wheel drive trucks so in your case only look for the 2 wheel one's, Here's a link that shows a picture and gives some more info and the right Tag numbers to look for. https://core-shifters.com/pages/ford-m5od-truck-trans-info

Here is a link to one of our site member's "alwill923" that did this Trans and has his details of the M5OD-R2 swap into his older 1965 F100 Pickup his workmanship on his 65 Pickup is of "Top Shelf Quality". So with some effort this swap can be done and the rewards of doing it will be great Drivability and much better MPG Economy too. https://fordsix.com/threads/1965-f100-with-240.82515/

Some other transmissions that you could also be swapped in and will bolt right up with the right parts to the 240 & 300 Six'es are the Borg Warner T18 & T19 (this one has all Synchro's), and the NP435 these are all very heavy duty truck 4 speed's with a Granny Low gear, so not quite as nice of a swap but often can be found very reasonable, but there isn't an overdrive unless you also install a Gear Vender's OD unit behind it.
 

BigBlue94

1K+
VIP
Supporter 2021
Supporter 2019
M5OD-R2 or ZF5 from a smallblock ford v8 or 300.

Im not well versed in the 2wd versions. 4x4 versions share a dedicated 5 speed transmission crossmember. Both use a concentric hydraulic clutch. The hydro clutch will destroy your firewall eventually. Bronco graveyard sells a reinforcement panel that should be used. After a few years of putting hydraulic clutches in, Ford redesigned the firewall to be stiffer, somewhere around 1990.

You will likely need a shorter driveshaft. IIRC the ZF5 has a yoke on the output shaft, not a slip fit. Not sureon the M5R2.

You will also need the transmission tunnel cover for a 5 speed as the 86 and prior covers are not tall enough for the 5 speed shift tower.

Also the block separator plate needs to be the 5 speed version.

There were a few ZF5s that were in 2wd cab n chassis that are a 4x4 transmission but with a parking brake drum in place of the transfer case. Not sure you would find one of these behind a smallblock though.

M5R2 can be found in 87+ F150 and Bronco.
ZF5 can be found in 87-96 (97HD) F250 and larger. A few F150 and bronco got the ZF5, only behind 300s. This was a special order option, trans code is Z, and only available in 87 and 88.

There is also the SMOD. Its a cast iron top loader style with Side Mounted shifter linkages and shifter mech. It can be found in 80s F100, F150, Bronco, and Econolines. Its not much different than your SROD. I would not bother with it.
 
Top