The Stovebolt Site Forums The Parking Lot Big Bolts spicer auxiliary trans

i have a spicer 7231D with pto that ive been researching and have found out what gear ratios it has and have even found exploded views of it, but i havnt been able to find out what size trucks it is meant for or its age. i have a 55 1st series chevrolet 6500,261 4spd 2spd hoist bed, that ive thought about trying to use this unit in. what im after is the overdrive,or is there a higher geared 2spd rear that would be a good swap? any info on the unit or any thoughts about this possible retrofit would be gratefully appreciated.

The box was originally designed for a truck a little heavier than what you have, but you would have room for it and there is nothing wrong with using it. I think the D ratio is a .86 overdrive. Its a lot of work to go about 9 miles an hour faster. Do you have all the shift linkage for it? The boxes are quite common, but the linkage is rather hard to find. You probably have the light 2 speed. They were available in 5.14/7.15, 5.83/8.10, 6.33/8.81 in GMC. I'm not sure what ratios Chev offered, but the rear ends interchange.

couple pics of my 55, her name is Rosie

light 2 speed? can you elaborate? my 54 truck shop manual says 6.13 high side 8.10 low side or an optional 6.70 high and 8.86 low. not sure which is mine but it sure seems like the second set. i have 2 linkage rods, 2 shifters and the mounting brackets for the unit. should there be more?

I don't have books on Chev but I would suppose what you have is an Eaton 1350 2 speed which were used in trucks of about 2 ton. They were available in the ratios I mentioned earlier. Heavier rear ends were the 16000 series. These were 3 ton which Chev did not build until the Task Force series. I'm not sure that Chev offered all the ratios that GMC did. However, a complete rear end from a GMC would fit a Chev. If you have everything to shift the auxiliary, you will be fine. It is often that people buy an auxiliary only with no linkage and then have problems finding linkage. If you have got all the parts, it would probably be the simplest way to gain a little more speed. The only modifications would be the drive shafts, but I'm sure there is a driveline shop near you.

Rosie is a good looking girl.

Look on top of rear end diff, you should see XN-xxxx, a two letter prefex plus four #'s.

XN or XR = 8.10-6.13 gear
XS or XD = 8.86-6.70 gear the four number will tell you the date of Manufacture

You are lucky to have the shifter...I've been looking for one a for couple of years.

thanks JD49 for the compliment. i put that steel deck HD bed on her a few years or so ago but thats gonna get sold, i have a 1962 Omaha Standard bed with round corners thats gonna replace it, it'll look more period correct. the diff in my 55 has the gear ratios stamped right on top,how'd i miss that, it is the 6.13-8.10 set. maybe a rear end swap to the higher geared GMC would be the way to go, the 5.83-8.10 GMC that crenwelge spoke of would probably get me 55-60 and the low side 8.10 would still give me the low-end grunt i already have. now its a matter of finding one thats not too far away.

crenwelge writes, "It is often that people buy an auxiliary only with no linkage and then have problems finding linkage."

Ah shoot, shifter is the easiest part of a retro-fit. I bought a used Hurst 4 speed shifter off Ebay, just the shifter mechanism, no lever nor rods. Perfect for an old Brown-Lipe transmission. Easy to fabricate mounts, easy to adapt on an old SM420 shift lever. Shifts rods are fabricated out of 3/8 inch rod lengths.

However, you do need an acetylene - oxygen welder or access to one, to make those adaptations. Bit of time, fun work, easy to do. Only requires good measuring and good planning.

Big bolt trucks have a perfect place for hanging a Brown-Lipe, right where the driveshaft is split. Always a healthy cross member there you can build upon. Hang the Brownie so the rear section of the driveshaft fits right, have the horizontal front section shorten to length.

Few days work, you are ready for the Daytona 500; got that overdrive! I declare, you can get your truck up to 55 miles per hour!

Billyray