When installing a new carpet, seat covers or headliner, place the new material in the sun for a while to allow it to become plyable. The job will go alot easier. Bob-"bobs409"
When installing new seat covers, use a plastic garbage bag over the seat bun, then slip the new cover over the bag. This allows the new cover to slide in place easier. The bag can either be left behind or pulled out afterwards. Bob-"mr409"
Need to remove a door/window crank but you don't have the crank removal tool with you? Try slipping a shop rag behind the handle. It will snag on the clip and you can pull it out. Bob-"bobs409"
Need paint for the metal parts of your interior? Find a paint supplier that has the old paint chip sample books. Interior color codes are listed there. (usually on back side) That code can be used to mix up the correct color.
Need an owners manual for your Chevy? Consider buying a good used one over a repro. An owners manual with light wear will look more authentic and you'll avoid putting another repro part on (in) your car. (I have a repro manual and the staples rusted!!! Can't they get anything right???) Ebay is a great place to find these.
If your doing your own headliner or recovering your sail panels, you will need some adhesive but avoid buying the small can of contact adhesive most vendors offer. While it's nice to have a can with a built in brush, 4 ounces of adhesive does not go far when doing both sail panels and headliner. Instead, go to a homecenter or hardware store and buy contact adhesive used for counter tops as it's the same stuff. You can get a quart for less than you'll pay for the little 4 oz can.
Seat belt webbing fadded? Get some common fabric dye found at any department store (sewing/craft section) close to or darker than your color. (if darker, leave soak for less time than called for) Follow the directions and be amazed at the results! Can really bring back life to some old belts and all for under 2 bucks! (tip #2: wear gloves)
Moisture builds up under floor & trunk mats and can rust/rot out trunk and floor boards. Consider removing these when storing/not driving your car.