yeah... on the ceiling mounts there is basically a plastic mold. Small speakers could probably be just drilled in and it would hold. Mind were so heavy that I actually used two bolts on each and then, like you said, screws that went into fasteners. Then I couldn't put the stock speaker grills on afterwards, and had to use the aftermarket ones. This is not typical of most 6.5 inch speakers though. Previosly I had Boston Acoustic 6.5's and they fit up easily. JL TR series 6.5 would have sit up there nicely too, but I have these big, heavy Alpines... they are the top coaxials that Alpine makes and they are massive.
I highly recommend the JL TR series... they are actually the cheapest JL's made, but they have won sound competitions when it comes to actual clarity... they are also easily mounted as their magnets are not too big.
2001 cherokee sport - Red
JVC SH707, stinger rca's and monster cables, JL slash series amps, JL TR interiors, Kicker L7 sub. Wet Okole seat covers, Class III hitch, Flowmaster Delta 40 series and K&N style intake, tow hooks, 2 inch BB, cross drilled rotors, 30" BFG AT/KO, some cheap pep boys driving beams. Next on the list: OME 2" spring lift, real K&N FIPK, locker? (I wish)