"Rear Adapter" is for a 144 WB
"170 most rear" is for the rear of a 170 WB
"170 ext most rear" is for the rear of a 170 extended WB
The option with butyl tape includes 64" of butyl tape. If the butyl tape is stuck to the plastic, put it in the freezer for 30 minutes. It will release, then let the butyl tape return to room temperature.
We recommend 3m Window-weld or Sikaflex 221 adhesive. Locate and cut the 14 x 14 hole. You can use the adapter as a guide to mark the hole. Stay clear of roof supports, obviously. Make a tape line 1/4" beyond the adapter perimeter. De-gloss the area with a Scotch- brite pad. No need to scuff. Just dull the paint. Clean with isopropyl alcohol and let dry thoroughly. Blow dryer if it's wet and/or cold out. Apply three 1/8" beads of the Window-weld on the face of the adapter. Then press the adapter down onto the roof until the adhesive oozes out the sides. It's not necessary to clamp. If you do, use a lot of lightly set clamps and spread out the clamp force over the whole surface area. Using the adhesive that oozes out, make a fillet around the adapter with a double gloved finger. Pull the tape within 15 minutes. Cure is fast on outside. Let cure overnight and then proceed with the fan install. We recommend using butyl tape for the fan install. Cover the fan flange with 1 1/8" wide tape. Place onto of adapter and press down. Use the screws that came with the fan, you may need the longer screws that we provide for the 4 corners. Tighten them very lightly against the fan flange. Some butyl will ooze out which you can trim off. Seal the adapter and onto the roof about 1/2" with Dicor self leveling sealant or Flexseal from the TV guy works well. Good idea to check the integrity and reapply the sealant every so often.
Van owner and/or installer assumes all risk associated with roof top mounted items and/or components. Van owner and/or installer recognizes and agrees that this product, and each of its component parts, is sold ?as is? and that seller makes no representation or warranty of merchantability that the product is fit for any particular purpose.