I have this set up on the 518 in the 36. It works very well with no need of a toggle switch. One catch I did not use the adjustable vacuum switch. I used the other switch that was supplied by PATC but is no longer available. It is GM #14014519 and is out of production. If you have a Pull a Part near you check out the GM vans they were used on many of them and are easy to access under the hood. I may have a spare if you are interested. Good luck!