LIONEL TRAINS #6-11131 844 NORTHERN STEAM LOCOMOTIVE

Contact Lionel's Service team at Talktous@lionel.com or call direct at 586-949-4100 and ask the service folks, It i quite possible they are out and have replaced it with another board with a different part number.

I have done this quite a few times and I always get what I need.

What makes you think you need a smoke unit?  It's likely that a simple parts replacement will solve your problem.  That board is no longer available through Lionel parts.

I CHECK THE PARTS AND THE FAN WORKS WHEN I JUMP IT OUT AND THE HEATING ELMENT DOES HET HOT. THAT'S WHY I THINK THAY THE BOARD IS BAD

If it's just the voltage regulator on the board, it can be fixed.  Since it's not available, I'd be checking into that option.

Ive has the same issue before check out this thread to show the parts to check. In my case the regulator went out and took out the IC (I think) been too lazy to replace the IC to see if that’d do it. 
link to that thread

https://ogrforum.com/...3-smoke-unit-6-11131

the board is still available it’s a PIA to find but just search this part number and it’ll come up 

691SSMUK02

you could also install GRJ’s SuperChuffer and that’ll run the fan. I recently did this with a new LED head light and it looks awesome. 

Right you are, there it is.  I'd order the 8 ohm resistor as well.  Don't put the old 6 ohm one back in there.