rebuilding Fox shocks, how to charge this style?

[megadesertdiesel]

I have rebuilt many shocks with reservoirs and Schrader valves, but this one has me curious. Neighbor had me rebuild some Fox shocks on his Polaris General and when finished he asked if i could rebuild the shocks on his 3/4 ton ram. They are single tube Fox shocks 2.25" OD cans without resivoirs or schrader valves. How do you charge them with nitrogen? My Google-fu is coming up nothing.

this style

 

[Grease Monkey]

I was going to have my fox shocks rebuilt off my 2500HD and opted for buying new. Coupe bucks more but new is nice.

 

[Sandkist]

You don’t charge them. Basically an air shock, sort of.