A stock 360 V8 in the Granny is able to rip the drivetrain apart in less then 10 minutes, my neighbour did just this in his 5.9 GC
Then it was damaged or not taken care of. My dad had a 360 with mods and it was beat on daily without trouble. They even lived with the SC kit from Vortec.
They are a A500 trans rig though so trans mods are needed, I'd also get a better converter with a stock 5.9. Making the Diff front and rear stronger isn't that tough but adding helical posi up front is a must. My dads had posi out back stock, if anyone building one doesn't have it back there they need it.
There are people out there thinking they can use a cummins in a Toyota LMAO I think the jeep would be fine with a 4BT in it and mods with the right trans work added. A 6BT would have to be more stock, the problem is mileage sucks stock compared to turned up. So I'd rather have a turned up lighter 4BT than a stock 6BT and the 400 lbs lol.
A 4BT version of my truck in a GC should make about 200 HP/ 450 torque and get near 40 MPG. I bet slower than a 5.9 limited but raging mileage. My dads 5.9 limited got 23 highway and 18 in town.
84 DC Shelby Rampage
86 GLHS 76
89 CSX 187
92 2.5 Turbo ES Shadow Convertable
70 R/T SE Challenger, supercharged 340
05 PT GT
I'm having a hard time finding a decent 360 Gr.C locally with under 200k on it . My good Jeep buddy has one with 370kms with stock everything. It was maintained from day 1. The original owner was a Jeep guy. It was a salesman's car for the first 10yrs, now it's his winter beater.
im in the process of doing the 4bt swap on my ramcharger . think ur better with the isuzu diesel but have u considered a vw diesel much lighter reasonable hp great fuel mileage and ur axles wont get destroyed . a litl tricky with the trans setup though . something 2 consider . BTW mopar 904 727 518 will bolt 2 bell housing and can use respective torque converters with the 4bt . google world products they can help with some direction ask 4 Ken . good luck with .
I think k you just pulled numbers from thin air there but to each there own I guess.
my friend got a 4BT and there not that great on mileage in a heavy rig. You have to push them pretty hard vs a 6BT. So far it responds pretty well to mods like the 6BT but the mileage isn't very good. Only got 16 MPG in the bread truck
So in a light rig they may hit 40, about 12 past my 6BT. But not in a heavy truck where they struggle.
Im surprised noone mentioned the OM617 mercedes diesel. Its the cheapest to get ahold of of any of the options, and it has the advantage of pre-existing adapter setups to get it to bolt to an ax-15, and using an ax-15 means you can use pre-existing crossmember, shifter, pedal setup, driveshaft, etc if you were to locate an ax15 GC.