| Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | The 4 speed vs. the 5 speed, the 4 speed is a 3 speed with a granny gear, the 5 speed is a 4 speed with a granny gear, closer ratios, get up to 55, then drop it into 5th gear.
Not all 5 speeds are direct in 5th. The problem with 5 speed OD trans.' , is to make it they make the 4thposition the OD, so there is a big gap between 3rd and direct, so with a load, frequently cannot shift up until hill is topped. Many came with 2 speed rear axles, this was more workable.
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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