For this to make sense, I have to explain my truck a little bit. Its a '78 power wagon sitting on an '85 4X4 1 ton chassis. It currently has a Magnum 5.2 with an NV3500 5 Speed. It was all I had at the time, and it worked well. Now, the kickers. I have a lead on a Magnum 5.9 with crazy low miles. There is a NV4500 that I could have in exchange for my NV3500. Only problem is this... My NV3500 is Brand Stinkin New. Seriously less than 10k miles since pro rebuild. NV4500 has around 100k on it. Will my NV3500 hold up to the 360 in that heavy of a truck? Would it be worth it to upgrade to the HD tranny with many more miles or stick with my lighter duty tranny? Truck rarely sees heavy duty towing anymore and I am not a clutch dumping tire roaster.

 

my opinion, get the new motor and keep your existing tranny, it will probably be fine, but you could start looking around for a rebuilt low mileage NV4500 after gettin the motor. You mentioned in your post that the nv3500 you had was freshly redone...Have you thought about talking to the shop who did the work and asking them if they thought it would be ok for the 360.

Oh ya and I wouldnt worry too much about the weight of the truck if you already have the transmission in it and its ok, the only thing that changes in your scenario is the hp/tourque of the motor. if the new motor has a lot more power than the old one then it might b an issue (and by a lot i mean a hundred or 2 hp or ft pounds of tq}....pretty sure the smallblock magnum motors are probably like smallblock chevy's where the size and weight are pretty much the same its just internal differences that decide the cubic inches.

 

i kind of wondering why you think you need a 360?

 

I dont really "need" a 360. A little more hit-it-and-get-it would be fine by me. Perticularly with a load. As mentioned before, I dont haul anything outragously heavy anymore, but I do flip vehicles for side money and they dont always run and drive when I get them. Also, my 5.2 (318) has a few more miles than I like. 5.9 is a trade for my 5.2. Free is my favorite price. Also, 5.9 has FAR less miles than my current engine.

 

Beaker - Thats sort of what I had in my head as well. No, I havent talked to the tranny shop, but it isnt a bad idea. Ill call them today. Anyone else with beaker? Keep the lighter but newer or go for the older but heavier duty?

 

i would be less worried with how many miles is on an engine and more concerned with the results of compression test or leak down test. those magnum have a plenum that eventually starts leaking which can cause the heads to crack if the engine was run too long with the cat being clogged.

 

Im doubting that it was run at all with the cat clogged, being as it has less than 70k miles on it. Rarely have I seen a cat plugged with less than 110-130k-ish. Besides, when it lands in my truck, there will be no cat.

 

I vote go for the NV4500, because I like overkill. I love mine. However the shorter gear spreads of the nV3500 could be fun too, so I understand that. If your 5.2 runs good, keep it. Magnum v8's last forever if treated right and maintained correctly.