Is it possible to change coupler on this Lionel six wheel tender truck?

When Lionel started outfitting those trucks with ElectroCouplers, they were re-engineered with a completely different coupler mounting method. Therefore, I don't think there's a "drop-in" way of adding a coil coupler.

The newer-style trucks are available from Lionel as 6918053T10 with a coil coupler, and 6918053T90 without.

TRW

Thanks.  For whatever reason, neither of the part #s you provided are producing any search results on google, Ebay or on the Lionel parts area of their website.   Is it possible there  is a prefix or suffix missing?

Oops. Part numbers have been corrected in the original post.

TRW

No, there is no "drop-on" way to do this.

But, you can certainly do this. The retaining clip - cap, as you call it - is a press-fit friction retainer. Very effective and easy to install on the assembly line. You can buy these at the hardware store. Remove it with pliers or some patient fiddling. 

Get an E-coupler and remove the old mechanical one. Then spend some time looking and figuring. All the new coupler needs to do is be on the existing post - retained with another/the same clip, perhaps - and be shimmed (washers or a spring - is there a spring?) so that it rides level. Not sure about any centering device on these trucks. It's a project, but this is model RRing.

Or: these trucks exist on modern, Electrocoupler tenders. I find all sorts of parts on eBay, or the Lionel website (parts). Maybe a new one, complete with e-coupler. They were also used on some rolling stock, and a newer piece may have some with more modern (drop-in) coupler mounts. Not sure.

They are nice trucks and a fairly good model of an actual heavy-duty freight truck.

Thanks D500.   I already was able to gently pry off the cap,  which had a spring and thin nylon washer below it.   The opening in the now removed manual coupler arm is identical to that of 2"coil couplers ERR sells (which I just ordered and is also the length of the manual arm I just removed).  Before I did that, I found there was a centering motion on the arm, likely a function the spring is part of, which presumably will be present when I install the coil coupler.  Given the original manual arm (a cast metal one)  was level based on the height of the axle, the replacement also should be.  If encounter any issue there, I have plenty of various sized nylon washers and spacers I can use to shim the coupler to be level.      

PaperTRW posted:

When Lionel started outfitting those trucks with ElectroCouplers, they were re-engineered with a completely different coupler mounting method. Therefore, I don't think there's a "drop-in" way of adding a coil coupler.

 

Update: I actually found that an existing version of Lionel coil coupler (the 2" long one available from ERR) is a drop in replacement for the manual coupler it replaced.   The vertical "axle" on the truck is a direct match for the opening on the "spoke" of replacement coupler.  About three minutes with a file  allowed me to reduce the height of the raised "nubs" on the bottom of the spoke, so that  -- once the new coupler was in place and the spring and retainer were reinstalled on the axle  -- the replacement coupler was leveled at the right height and could move to the right or left while retaining a smooth, consistent centering motion.     

D500 posted:

No, there is no "drop-on" way to do this.

 

 See above update.