M725 Mod questions HELP

[monty]

I have a m725 that had a sbc in it and was either looking to replace that engine with another sbc. It's currently running stock axles and 42inch superswampers, my plan is to use the truck on/off road doing some expidition type exploring

Questions

Can the transmission handle 250hp engine and freeway speeds or should I look to change it out to a 5 speed or??

Also how are the np200 transfer cases at running down the freeway or offroad?

OR

I have a really rusty m1008 that runs/drive great and i'd that the time to swap the 6.2 engine,trans,transfer case. But without an overdrive i'm not sure if the 6.2 would be in it's happy rpm either.

I've tossing around the idea of swapping the axles from the m1008 under the 725 also to have more strength and the locker.

I want to get the truck on the road ASAP and i'm looking for input from others as to what their experiences are and what they think.

Thanks

[Barrman]

CUCV engine, transmission, t-case and axles would be your fastest, cheapest and most dependable swap from what you listed out.

[monty]

I was thinking of the CUCV also, and the thought came to me after reading your thread on your 6.2 swap.

[Barrman]

You will still be limited to around 55-60 mph unless you stick to your 42" tires. But then you won't have any low end grunt and hills will kill you.

[monty]

Thanks again for the reply, i think i will use the 6.2 and swap on the 6.5 turbo parts that i have. Hopefully the turbo will overcome the tire size on the hills. I`d like to convert the rear into a mini camper and start to explore some remote northen WI woods.
I really like your 715, you did a great job on it.

[Barrman]

Thank you. The turbo should make all the difference.

Look at the Alaska brand pop up bed campers. They would be just about perfect for a M715. They work great in a M101A3 trailer too.

[jeeper]

I think the term "fastest" is a relative term in this case.

Are you planning to do the work yourself? What do you consider highway speeds? How important is low end torque?

The fastest and cheapest option is to replace the small block chevy with a small block chevy. You could have that done in a weekend. If you used a 383 stroker you'd have plenty of torque to drive as is.

I had a 305 small block in my 715 last summer. It was fine for cruising and for off road. I could do 55 with it but I didn't. I wouldn't call it a power house but it wasn't that bad.

I have a 6.2 diesel in mine now with a stock drive train. I am content with the power and the slow top speed. I keep it at or below 45 mph. I've never driven it on an expressway. The minimum speed here in Michigan is 55 on the expressway.

Keep us posted whatever you do. And take pictures.

[glenn]

Swapping the CUCV drivetrain over would probably be the best/easiest/cheapest course of action. These rigs have the aerodynamics of a brick so make sure you take that into consideration when planning your top speed/fuel mileage.

[monty]

Barrman.......... It's a m725 so it's set up for a sleeping arangement in the back, I'd like to added a roof rack to it to store more gear. I have a m101a3 and have looked at a camper to slide into the back of it depending on how many people I have with me.

Jeeper.....I also looked at a blow through turbo on the sbc to help with torque, I get a little excited cause I want to get out and drive it so I need to slow myself down and get it right. I do all my own work, I have a hard time paying someone to do work I know I can do myself. I then find myself overly scutinizing their work, so it's better if I do it myself. I owned my own business building drag cars for about 6 years so welding/fabricating is right up my alley . I consider highway speeds to be 60-70 to be a decent highway speed. The spots I'm looking to go exploring are 250 to 350 miles away.

I may look at taking a trip up to the U.P. with the truck the two tracks and logging roard are some of the most awesome trails i've been on.

Whats the deal with the transmission /transfercase ?? I heard the don't like sustained rpm cause they'll puke out oil??

[fishtail]

The stock transfer case, the NP 200, doesn't like continuous speeds at or above 55 mph with stock engine rpm and axle gearing. You'll burn out the seals and wreck the bearings. And it'll leak bigtime. Most of the trucks are like that now with these.

The transmission is pretty bullet-proof. Nobody ever talks about wrecking one of those.

If you get thru Stevens Point, I can show you all my crap if you got time.

Scott