[mrchaotica]

There are four different possible consoles:

• '98 to 2000: fixed cupholders shoved up under the dash
• '01 to '03: cupholders that swiveled to the side
• '04 to '05: still swiveling cupholders, plus a huge fixed armrest that could contain a CD changer
• 2006+ (i.e. on post-facelift): cupholders next to the E-brake.

[Years are from memory; they might be off.]

I, too, like the 2006+ console best and plan to eventually upgrade.

 

[mrchaotica]

06+ MODELS interior is slightly diff, don't know if the 06 interior will fit the a4 chassis

The post-facelift Beetle is still on the A4 chassis (which is why it so badly needs a redesign -- it's now two chassis revisions behind the Golf & Jetta, going on three!). The interior is nearly identical, except for the center console and some minor details (thin chrome rings around the air vents, hazard light switch above the radio instead of below the A/C controls, etc.).

if you're looking for OEM direct swap, you can go up to 05.....

And '06 is easy too, only requiring the e-brake mount to be modified. (Go read the thread Th1rt3en linked to; you'll see!)

To the best of my knowledge, the only hard swaps between pre- and post-facelift Beetles are bumpers and rocker panels.

 

[mrchaotica]

Can you add one to a 99 bug that didn't come with one?

Add one what? A center console? All New Beetles came with that. Maybe you're asking if you can add an armrest to a center console that didn't come with one?