Part number guru's- I need your help ! P/N 3874129

Okay guys I am posting this for a friend. I asked a similar question a couple weeks ago. I am by no means a mechanic so please forgive me for my ignorance. My friend bought my 78 Dodge motorhome that has a 360 in it. It is stranded in the middle of his drive. He has checked everything and determined that the "ignition spark control" or "spark arrestor" ?? is bad. The part number on the unit is 3874129,the only other number is H8D. It is a 3 prong oval plug and is green in color. He has been told that there were 3 colors - white/orange/green. When checking with the dealers this part number is listed as a "switch" and is marked as discontinued. Any suggestions where he might be able to find one or what the "official name of this part is"? Thanks in advance for any replies- Ron

emission speed switch.

Now, what's that exactly ? dunno... will check

NachoRT74- I appreciate the quick response and will wait to hear back from you on rest LOL- Thanks, Ron

Anyone else ??