here we go with this....
lol i went through it after i bought my M35a2. and i don't have a ring yet.... thanks to my hard top roof.
the correct set up is a M66 ring, which for the correct GI set up will run you more than your truck cost.
the poor mans way to go is get a soft top roof if your truck doesnt already have one. fix up a german MG3 ring to it. that will run you about $500 total. the super poor mans set up is pictured below and involves pipe and welding. but i could never find a bracket to mount my 1919 on so i cant build this eigther, but if you already have a pintile it is an option.
you can get M66 rings here
http://www.bmgparts.com/mount.html
and you can get MG3 rings from RTG parts.
or you can do what i do after i decided i didn't want to fool with it and shove your MG of choose through the window and make use of the bipod.
threads to read..
http://www.steelsoldiers.com/deuce/31602-30-cal-mount-deuce.html
http://www.steelsoldiers.com/deuce/37759-30-cal-mount-deuce-made-easy.html