Figured I'd post this here for those who may have not seen it elsewhere.
Several others have performed this as well. Some may like them, some don't, but this is an easy swap that can be performed in an afternoon.
'88-98 manual seat bases bench and bucket, are comprised of of the same components.The risers are interchangable;
If you have a factory bench, unbolt the horizontal bars that go across the trans tunnel, and you have the riser for one seat.(obviously you will need a shorter spring).
You will need another bucket or bench, set of risers for the second seat. There is some variation with extended cab trucks that have rear seat entry. I have never owned an extended cab truck. You will need to drill 4 holes for the inner mountings of both seats.
I have owned 4 C/Ks since '88 (88,90,94& 99)All of them had dimples (markings) in the floorpan for factory bucket seat mounts. My '94 suburban had the un-threaded nut and backing plate welded in the proper location beneath the un-drilled floorpan.
Mid size '92-'00 pontiac bonneville (and other GM midsizes on the same platform) bucket seats will bolt directly to '88-'98 seat risers with NO MODIFICATIONS, they both share the same riser-to-seat bolt pattern. These seats are cheap, and plentiful,and come in cloth and leather,recline and power lumbar was avialible.
I purchased 4 seats for my suburban for $100.00
In the case of SUV's, the rears are not straight bolt in, new holes and mounting points have to be fabricated, but this mainly addresses the front seats.
The power seat units in '88-'94 and '95-'99 C/Ks will also bolt directly up to these seats with no modifications.
The Pontiac seat bolts directly to the C/K seat motor without modification. Therefore, the new seat is at the correct height for the truck, the riser already fits the truck, and no fabrication to make the Pontiac mechanism the proper height, or bolt pattern is necessary.
Check the pic of my '94 sub. The driver side power unit is from a '98 Tahoe, and the passenger side is my original '94 bench seat riser.
No mounting holes were enlarged,slotted,or modified in any way.
I find these seats to be EXTREMELY comfortable, and they fit the wide physical dimensions of the cab nicely.
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In my '91 reg. cab...
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Bench seat riser. The end sliders are identical to bucket risers. If you have a bench, unbolt the cross bars, and you have the riser for one bucket seat. You'll need to get another pair for the second seat.
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Use the outer two original seat mount holes from the bench as your starting point. (passenger side shown)
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The inner holes that need to be drilled for the inner riser/slider need to be 13 and 3/8" inward from the original mount holes, center to center, and will end up on an embossed (raised) section of the floor pan intended for bucket seat mounting. (driver side shown)
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If you are using a Bonneville seat, or a fullsize GMT 400 bucket, I strongly recommend bolting the riser to the seat, and determining your measurement this way.
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The hole distance from front to rear (on one riser) is 10 and 5/8" The distance on the slider portion where the seat itself bolts to the slider is 14" There is some room for adjustment, or possibly another seat option, as the front holes are slotted.
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Underneath on the passenger side, there is a knockout portion on the heat shield for the exhaust to access where the inner front hole will end up (in the recessed area)
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Passenger side, inner rear hole. This area is unobstructed.
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Driver side inner front (I did not driil this, because in this case,I installed a 60/40 and the holes are on the transmission tunnel)
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Driver side inner rear.
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For safetys sake, you should weld a nut to a piece of 3/16" (minimum) plate roughly 1 1/2" x 1 1/2" square, or a very large fender washer to prevent the bolts and nuts from pulling through the sheetmetal floor pan in the event of a collision.
