Congratulations on a successful transplant. 3700 is still a high RPM for cruise. If you anticipate long cruise trips, an OD transmission such as NP-540 series, Clark with an O in the MN, Advance Adapters, I believe, makes an OD unit that bolts in front of main trans. These and most similar units bolt right in with shortening of the driveshaft required.
Ed
The Advance Adapter Overdrive (Ranger Torque Splitter) is no longer available. They work great though! I had an older cast iron one, and ran it for a few years but, the countershaft and needle bearings are shot so, I pulled it out.(of course, it used non-std parts and they are no longer available!).. I sure miss it! One of these days, I will find another one, or maybe have mine fixed to bring it back to life!
Congrats on getting the rear end swapped out! I run mine at 3800-4K for 8-10 hour trips quite often. Yes, it is noisy, but doable... and yes, it will suck down the gas at that speed! (My 6400 has a 350 in it)
