I have had my Campulance back now for almost two weeks. I live at approx 6500 feet. Thats pretty high for a non turbo diesel. I took it on a trip to Overland Expo up and down some serious grades. On that trip I averaged 10.85 MPG. I was able to sustain speeds of 75 except on steep grades. I was as slow as 50 mph but was very impressed with the new trans. I was stuck in 2wd as there was a problem with the new T-case or so we thought. Turns out the shift lever cam for the Tcase (used the np208 shift cam lever) was clocked wrong and was hitting the T-case and not able to shift into 4 wheel drive. Problem is now fixed and the truck went back into the shop to wrap up the install. Now everything is done and I have been driving her just under two weeks locally at an average of 6500'. My Highway mileage is 14.86 mpg relatively level ground at 55/65 mph. My combined city and highway (approx 75/25). 10.64 MPG. The problem I can see at this altitude is the lack of air getting into the engine. At sea level I was shocked at how much MORE power my M1028 had. I was truly shocked. To maintain speeds of 65 mph and up I need to keep her into the throttle on any slight incline. This would not be the case at lower altitudes. So in those cases you would see even a greater MPG gain. I suspect adding a turbo will greatly increase my mileage.
AROUND TOWN: The new 700R4 is amazing around town! I can actually pull ahead of traffic from a red light! You won't win any races but the deeper first gear of 3.06 really helps get my 6,000 lbs plus Ambulance rolling. Its a whole new vehicle. The driving character of the vehicle has completely changed for the better.
CRUISING THE HIGHWAYS: As I said before at this altitude on any incline I need to slightly keep the throttle up a bit. At lower altitudes I know this would not be the case. Remember this is a Ambulance. With a M1009 or M1028 M1008 I suspect You would not have this issue. Steep grades still present a problem but not like before. Its still much better than stock. A Turbo would solve all of these problems.
OFF ROAD: Well I was pretty impressed with the stock set up. Now that I have a lower 1st gear and a Lower Low Range she is even better. In fact it is much better than I expected. The NP241 does indeed shift much much smoother than stock NP208. Its a very nice combo to have.
PARTING THOUGHTS: At lower altitudes this would be an exceptional Trans and T-Case combo. If you live at altitude then I would highly recommend Installing a Banks or other Turbo system. For me it is a must. On smaller lighter vehicle like the M1009 then I suspect it wouldn't be as big an issue as it is with my heavy Campulance. Would I do it again? Yes I would. The increased drivability of the truck is HUGE or as my favorite President would say "YUGE"! At the end of the day it brings your 80s Truck a few steps closer to modern day highway speeds. If I want I can cruise 75 mph and up and pass people as needed. I could only dream of that before. (I am still running my 4.56 axle diffs)