I have a fl350 and 2 fl250's and i plan on switching the rear hubs on my 250's to the 4/110. I saw somewhere else some 1 wanted to do the same on his 350 but the only answer was an adapter. Is that my only option to change the 350 rear to a 4/110 and if so where can i get the adapters

Atc 200x hubs are the same spline and a 4/110 but the need to be machined on the back side to hold the dust seal for the carrier(if that's what it's called). I had a set of these I was going to make work with some paddles on aluminum rims I had. For the aluminum rims I had grind the little time locator tabs off the hubs. I since scrapped the idea. I'm just going to find a set of rims for sand tires and keep the steel wheels.

so i took a look on ebay for atc 200x hubs and it would seem they r the same as the 400ex hubs can any 1 confirm this cuz they r the same hubs used to convert a fl250 to 4/110

Try the set that you've got for the 250. I think some people space them out but then you don't have the dust seals. Not so good.