If you running a super turbo engine the 71741X gear box is going to be weak but if you running a normal 603 or 103 the 71741X is going to be fine I been using a 717410 in a 603 for the last 3 years and is doing fine and a 717411 in my 87 300TD for the last 4 years and is doing fine

Torque will kill a gearbox more than power, most diesels are not going to exceed the RPM limits of the bearings and gears in the gearbox.

In a gas engine you typically have less torque for the same horsepower rating, so a 300hp gas engine will be much easier on a transmission than a 300hp diesel, which will typically generate close to twice the torque.

Driveshaft
 

I'm wondering if somebody could clear up some confusion about the drive shaft combinations. I'm about to put a 5 speed in my 87 TD Wagon, can I use:

190E Front shaft >> 300TD end shaft

Or does it have to be:

190E Front shaft >> 300E end shaft

You can not use a 190E front drive shaft with a 300TD or 300E end shaft different end size according to a member here you can use a 190 front drive shaft with a 260E end drive shaft

Here's how I did it.
Another OM603 5 speed swap

You need the rear DS half from a 300E 2.6 or a 260E (they're the same thing, different names for different model years)
You'll also need the smaller differential input flange from a 190e or a 260E.

And how difficult is it to pull those differential input flanges?

Easy if you have the correct socket and an impact gun.
Mercedes 30mm Deep Socket ASM-100-30A 126589020900

Removal is simple. Installation, not so much. If you over-torque the nut, it will compress the internal crush sleeve which sets pinion bearing preload, and quickly kill the bearing. And no, you cannot just loosen it a little. The only way to fix an over-crushed sleeve is total diff teardown & pinion removal to replace the sleeve - not possible as DIY for most people. The factory procedure uses a very expensive rotational torque measurement tool to properly set torque.

If you go down this road, be very, very careful when torqueing the pinion flange nut.

:blink:

And how would you go about not over torquing that nut? Would you index the position of that nut on the threads, and only move that nut to that indexed position when your retorque?

When R&R'ing the flange to replace the seal, yes, I believe this is what most mechanics do. When using the same flange and same nut this should result in pretty close to the proper torque.

However, if replacing the flange OR the nut, this may not work, particularly if the replacement flange does not have the exact same depth/dimensions as the original.

:boat:

I marked the angle of the nut before removal, swapped the flange and then re-tightened it to exactly same angle. That was 36k miles ago and my diff is still alive and well.