I'm needing to do a tuneup on my 72 dodge motorhome (chassis is a 1972). But I'm wanting to make sure I'm thinking right. All the points, condensor, cap and rotor are the same as the 440 right? I know the plugs are different and I think the wires. But when I got to the store to try and order anything no chain store even shows that the 413 is on the m300 chassis. I'd like to get new plugs, wires, coil, cap, rotor,fuel pump, etc.

only the cap/rotor could be different if it is a dual point deal (& I wouldn't think that it would be in a MH). I'd get the number off of the plugs & have em cross it to a NGK (they have a good rep) or any brand really & you could go a step hotter on the plug as needed

You probably need to look in the HD truck section, if they have books.

RockAuto has the 72 M300 listed, but no 413 either.

It should have a electronic iugnition in it, but you never know what the motor home makers used on parts on there builds Look at the distributor with the cap and rotor off and see if it has points If so take them with you to a good, not a cheap, parts store so you get the proper set of points on the first visit The 413 motorhome motors are a completely different animal than the regular passenger car motors where, the industrial and motor home motors where designed and built to be used in severe duty appications with all long lasting H.D. parts Not so after Mopar stopped making the 413 M.H. motors, the non 440-3 motorhome motors where probally the same as the standard non HP passenger car, van and pickup motor where The 440-3 had better heads and valves along with extra cooling for substained heavy hauling like in a class A motorhome or larger truck sees IHTHs

Asper my 1988 champion catalog section vans/trucks/buses 1972 dodge MD-TRUCKS v8-HD 413 6.8 4V N5C plug.
Asper 1993 NGK catalog N5C crosses to B6ES or BR6ES.
As far as cap/rotor points/condenser ETC ETC its all the same.