Tom - so who did the Sleuthectomy (nice play with words... good 'un)? DIY or Carl or ? Do the MTH units 'go right in' or is some further disassembly required? Hmm - are the MTH units still available? I really do like both the mikado and the pacific from the mid-aughts, but the smoke units really do suck. I haven't fired up the smoke unit on my new Berk (Flyerchief) yet - hopefully it will be ok with the Anormal smoke fluid, of which I have a lifetime supply (works great on my old Gilbert steamers).
Check the link that Carl posted above and you will see what is involved. The MTH units may still be a available. I bought a few when the closure announcement came out. The part number is on Carl's page.
Anormal works fine with Lionel's smoke units in my experience.