there was a post i here about the site gages with pictures but I can't seem to find it :? and I have pictures of mine but also can't seem to find them
I used that same heavy clear plastic like I use on the jetskis can't begin to gin you a name brand though I think it was Des or Fp1201 that had some really good pictures of there site gage
I just used clear 3/8 inch plastic tubing. I had to vent the top to get an accurate reading. I just vented it back to the accessory case. Here's a picture of one but it is not mine. That oil doesn't stay that clean. A few hours of run time and your oil will be carbon black.
It was really simple and so far has faired very well:
The tubing is 1/2" clear hose that's available at most hardware or big box lumber stores. I was very skeptic about doing this, but it was the best modification I could have done!