| Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Jack up one wheel after you put the two speed in high, count revs. Most truck two speeds are all geared slow or slower, so adding some kind of OD might be the best solution. Also depends on what engine, you have . 69Cuda must have a V-8 judging by his RPM's, so a 292 will cruise at a lower RPM.
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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