| Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Many use the location of that unit to install a ‘Brownie’ OD unit to enable higher road speed. Brakes and steering should also be upgraded as well. If you are going to keep the 261, then there are also Watson OD units that would work. All these units are long out of production, no parts are available, so searching in wrecking yards is best. Many do not know what they are, so if one asks, frequently get a blank stare, must just look around. Look for another shift lever in cab.
Be aware, brakes should be mounted on rear of aux. transmission, otherwise, when in neutral, no main transmission brake will work.
Brownies come in sizes, first number, I. e. 5531 indicates ENGINE torque input. 5xxx and 6xxx series would work for your truck, 7xxx and larger would be too big.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
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