Posted by Charlie on December 04, 1998 at 20:22:02:
I wrote a 1 page letter to Power Wagon Advertiser Dec 98. I believe a Gear Vendors 0.78:1 planetary overdrive will work behind a NP200 transfer case (with a 2-piece rear bearing retainer, which can be obtained as a NP205 part if your TC has a 1-piece), with their NP205 adapter. They have a coarse spline coupler sleeve. It works in 2WD only. The ratios will be 4.55 with 5.83, 3.81 with 4.89. This allows repowers with V8s and diesels to obtain the full speed/power potential with 4.89s, and to cruise at proper cruise rpms: 2060-2560 at 60-70 mph with 36-39" tires. Flatheaders will turn 2720 at 60 with 9.00-16 NDs, i.e. cruise at 55 at 2500. And repowers lucky enough to have overdrive transmission can keep 5.83s. It shifts like an automatic with a sprag mechanism, it has it's own oil pan and pump. Their phone # is 800-999-9555.
Charlie