how to remove seats from conversion van

[PeterF]

I just bought a 93 Chevy G20 conversion van with 119k miles on it. The vehicle is in good condition and seems to run great.
Does anyboy know how to remove the seats from this van? There must be some trick to it that I have not figured out.
There is a spring ring under the seat that attaches to some kind of plunger. It moves up and down, but the seat will not move.
I can see the bolts and nuts under the van, but the heads are covered by the metal base of the chair and prevents me from unbolting the whole seat.
Any help would be appreciated.
Peter

[schorchin]

There's a lever under the seat to release that plunger, pull the lever and turn the seat about 1/8th of a turn and lift up.

[Junkerman]

Greetings:
I think it depends on who did the conversion... They are not all the same. Several companies buy raw, or very basic, vans from GM, or in some cases, will do the work on one already owned by a private person.
I have a 1989 G20 conversion, and there are two different kinds of seats, not counting the rear bench. The twp in the middle are the easiest to remove. They have a lever, as the previous poster mentioned, and this lever is held in place by a spring-like handle to prevent accidental seat moving, such as in a crash. You must push this spring handle down to be able to turn the main lever. There is then a pinned shank that has to align with a slot in the floor pan, or what ever you want to call the mounting plate for the seat. When aligned, the seat can then be tilted backwards, (easier than forwards) and more or less manhandled out of the way. They are sort of heavy. The two front seats do not remove this way, the only way I know of is to unbolt them much like you would in any other kind of vehicle. They have the same sort of turn and slide mechanisims, (move forewards or backwards, as well as turn from side to side) but lack the quick release of the two middle seats.
The rear bench is easy once you know how, but takes a bit more time. On mine, there are 4 (four) knobs that are threaded into the floor, through these interlocking brackets. These brackest are a sort of 'tongue and grouve' affair. Made of aluminium. they can get sort of sticky, and hard to slide into or out of each other. The knob can also be hard to turn by hand. But once you have all four removed, you can just slide the bench seat out the back doors. (If you have a spare tire mounted on one of the back doors, you might not be able to open that door far enoung, try removing spare first) My version of bench seat folds flat(ish) for a bed, and I find it sometimes easier to first fold it flat before unbolting from the floor. Afterwards, it's next to impossible to fold up or down without help. I keep all the moving parts for this seat well lubed with a silicone based grease/lube... As dirt and such, along with heating/cooling cycles tend to tighten the bolts over time. And like I said, the aluminium parts tend to be 'sticky' anyways. (I vacuume out the bolt holes everytime I remove the seat, to keep dirt and such to a minumum)
Hope this helps. Like I said, yours may differ, depending on who did the conversion. Mine is a " Silver Touch" by "Trans-Con", if that helps any.
Good luck:
Junkerman