Timko-upgraded 6-18009

I would say 10-12 modern cars. If I remember your 18009 does not have traction tires so your wheels will slip before overloading the motor. Do it. You’ll love the results. 

I have a Reading T-1, sans traction tires. It will pull at least 20 freight cars on the ckub's non-level layout. Yes, the wheels slip, especially starting the train. It means I have to jockey the throttle to get the consist rolling. Just like the real thing.

I was pulling 25 scale freight cars around our club layout with the Reading T1, that includes a long 2.5% grade and a couple of lesser grades.  Mine has the Timko can motor upgrade, the Cruise Commander/RailSounds Commander, and of course the Super-Chuffer and Chuff-Generator.

I'm personally not a fan of the little Mabuchi RS-385 motor which is typically used in these conversions.  I just don't think it's appropriate for a heavy, full-sized scale model.  The Pittman 8692 is a better quality motor about the same size as the Mabuchi.  Another option might be a 7-pole K&D motor (as used in US Hobbies O scale steam locos during the 1950s-60s.)  These can sometimes be found on the popular internet auction site.  Open frame motors like the K&D are a better match to the Pullmor's form factor.  In other words, while a "can" motor is cylindrical, these K&D style motors are about the same shape as the Pullmor, with a field winding protruding on one side.  Unlike the Pullmor, all of the motors I mentioned are designed for DC operation.   So you'll have to use a Dallee #400 E-unit or a (temporarily) discontinued ERR board for reversing and control.

Personally, if I were ever to proceed with this conversion, I would choose NOT to have the wheels grooved for rubber tires.  This is a weighty loco with a fairly tall ~100 mph gear ratio.  If you put a heavy load behind it and run on sharp curves at slow speeds, the rubber tires will prevent the wheels from slipping.  Some excess current will build up as heat, and this will shorten the life of the motor.  Also, you'll have the nuisance of periodically changing the tires.  My $.02.

Yes. I even had him add the ERR Cruise Commander/RS, something I usually do myself, but he had the engine for the upgrade, and I was feeling lazy, so... I had to replace the running board steps, as they got lost somewhere in Ohio; they are separate pieces.

I do not pull long trains (10 - 12 freight cars), but it seems to do just fine. I don't like traction tires anyway, so the occasional slip on startup is a nice prototypical touch. The loco runs fine; I have a 1990 #5340 J1e that I would like him to motor-upgrade (I'll do the ERR). I need to get to it, as we keep losing modeling resources to retirement. 

(Rant: this is tooling that has never gotten the respect it deserves. The detail is very good - and mostly cast-in, even - but the Pullmor was never a good idea, the pilot deck sits too high, and, where-oh-where is the rest of the valve gear? It just looks stupid without the combination lever, the valve stem and the rest. I have bought some parts from Lionel (Niagara; they looked more promising than the 700E pieces, which I also may try), and I hope to fill in the "valve gear blanks" in a reasonably convincing way.

Lionel, this tooling is a wasted resource. It even has nice, big, scale-y pilot wheels, something your L2a could sure use. Of course, back in the day, these locos were made in Korea by way of MTH, and MTH usually does the pilot wheels better, so...)

Mine; can motor and ERR. And dirty. I have got to get some good photos of this loco - after I "complete" the valve gear (if and when).