| Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | NP-540 series have a nice 4th that lets one go 55 or 60 before shifting, no OD though. They do have rare OD ratios, however the gear splits are not very useful.
If one wishes to replace a 420, with something with a large retainer, it is easy enough to bore out the bellhousing.
Ed
Last edited by EdPruss; 09/05/2019 4:13 AM.
'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.
| 
