i have just installed a decoder in my kato n scale csx cw44ac & cefx ac4400 locomotive. now that i try to put the shell back on it want snap back in place like it would with the factory decoder. is there some type of cutting you have to do in order to make it fit properly. the problem i have with it is when i snap it down in the front it raises in the back, and when i snap it down in the back it raises in the front. the decoder i have is the mrc n gauge dcc decoder item# 0001642 for kato sd70 mac & ac4400. or do i have the wrong engine for this decoder. any help would be greatly appreciated. thanks in advance.
Does it look like it should fit? There’s a physics thing that says two objects can’t occupy the same space, which I think must be tougher for N than the HO I’ve done. Try to make sure the decoder and any wires are fully seated and out of the way of the shell. Is this one a plug-in or wired?
Jim
The MRC sound decoder? You need to make room for the capacitors on the board in the radiator area of the 4400cw. Also, you need to file down the smokestack support casting in the inside of the shell.
In terms of the 70 mac, it should just fit…
David B
Sounds like you have the wrong decoder; the 1644 is for the 4400 and sd70. It fits in with no modification needed at all, very easy installation.
Pos decoder though 
jim- it is a drop in decoder from mrc #1642 for kato sd70mac & sdac4400.
mailman56701- i thought these were the right decoders as it says on the package it will drop right in place and no modifications needed for the sd70mac and sd ac4400.
davidmbedard- do ou have any pictures of this work being done to one of the shells, or do you know of anyone that does the work and i will pay for it.
Ive installed a bunch, but because of the rules I cannot offer you my services. Your best bet is to see what has to be modified, then modify it.
David B
Nothing would preclude you from offering some help offline, David.
-Crandell
According to MRC’s site, the 1642 is for Kato’s P42 and E8 locos. Sounds like you may have the right bag, with the wrong decoder inside
The 1644 is for n scale sd70s and 4400s. I had one, wasn’t impressed, fwiw. Sound was ok, I’m not picky, but the motor functions of the decoder were poor and it comes with BLUE leds for the lights.
well that means i have 12 of the wrong bags then. as i ordered these from my dealer in memphis, tn whom ordered all of these decoders direct from the manufacture. i was there when he ordered them over the phone with the woman, and he asked are these the right decoders for these engines and she said yes.
Don’t know what to tell ya then. Just going from personal experience and MRC’s website.
Fwiw, the 1644 is a direct replacement for the stock circuit board. Easy as it gets installation, with absolutely NO shell, or any other kind, of modification needed to the loco.
maybe i can contact them and maybe they will do an even exchange. what will a try hurt.