Just wanted to follow up and say that I got my Polaris 400 fixed and back together.

Thanks to everyone that offered advice and especially the links to Ronnie's ATV parts. It was great to be able to look up and order parts from their on line site. I got to looking at the exploded views of the transmission and could see it would be pretty easy to wrap several hundred dollars up really quickly in some of the shifter forks and sliding  gears & collars.

Turns out I was able to find a used transmission and shifter lever box on Ebay that was significantly less than what just a few parts for mine would have cost. After inquiring about it's condition and being told it was in fine shape and had none of the symptoms mine was showing I took a chance on it and won it on Ebay. I got it here and swapped it out with mine.

Not an overly difficult job but there sure is a lot that has to come apart in order to do the swap.

At that time I noticed I needed the rubber boot from the air box to the carb and the rubber intake where the oil injection line enters. I ordered those from Ronnie's as well as a Clymer repair manual.

I just got everything back together and running the end of last week. Everything works like it is supposed to and I once again have reverse and high range and it once again shifts like it is supposed too.

Sure is nice to have it back in operation as I sure did miss it for spraying around buildings, poles and the like. It's also nice to have the top end speed again vs being stuck only in low range and not being able to back up. 

Thanks again to everyone that offered ideas,suggestions and links.