300D rear shelf mounting depth/speaker recommendations

[ltrain300D]

I've got a 83 300D, with some nice infinity 5.25" speakers back there, and they sound OK, but my plans are to get a decent amp (for all 4 speakers) and get some 6x9's for the rear deck. First, I know a few have done this - it just requires some cutting of the shelf, but - is there a max mounting depth I should be looking for when looking at speakers? I'd like to get a set of Infinity's to keep it all the same - maybe the 692.7i or 693.7i - I believe they have a mounting depth of 3 3/16" - which is top mount I am pretty sure. Will that fit? I've used the search and haven't been able to find a clear answer on max mounting depth.

Or do you guys have some recommendations as to some 6x9's that you know will fit and sound good as well?

[Marshall Welch]

Speaking from experience with my car, an '82 300D-T, I think you can access the rear speaker boxes through the hole on the rear deck for the first aid kit. Remove the first aid kit, and you'll see a couple of screws on the bottom of the box. The box lifts right out after removal of these screws.

On my car at least, the rear speakers are enclosed by sheet metal in a "bowl" shape. You should also be able to make sure that 6X9's will fit there. You'll also see that the fuel tank sits beneath the rear deck- be careful when drilling.