Guitars and Bass bodies come in 2 categories......  carved top (post/stud mounting) and flat top (can be post/stud mounting or flat mounting).

Post mounting...

If you have the very common 2 piece Tune-o-Matic with the 3.25" stoptail piece and 4mm or 6mm bridge posts (shown, left) on your guitar, you should fully understand each piece as it relates to installing a Kahler 72xx. The 72xx models are best for this situation because they are designed for arched or flat top bodies and can attach to the Tune-o-Matic posts. They are better suited to accomodate the higher string height of a Tune-o-Matic as well as compensate for steep neck angles like on LP's. Almost all guitars that use a Tune-o-Matic bridges have a steep neck angle as opposed to a Stratocaster type guitar which has a flat shallow neck angle.

So here is the lowdown...

The stoptail piece (picture above, lower piece) is slid onto the 2 big slotted posts and holds the ball end of the strings . The Kahler mounts to these posts. (picture right)

The bridge section is between the stoptail piece and the bridge pickup and has strings slots. (picture above, upper piece)

The Kahler uses the old bridge holes for a new purpose... riser wheels. (picture left) They act as levelers. So between the 2 stoptail posts and the 2 bridge riser wheels, you have levelers on each corner to keep things trim and proper.

The 2 piece Tune-o-Matic has a gap between the 2 parts. You generally have 2-1/8" to about 2-1/4" between the bridge sections small E saddle notch (which should be set to the scale length) and the center/middle of the stop tail piece. Knowing this information and assuming you are swapping from a Tune-o-Matic to a 72xx Kahler and you know that the studs are located properly and all is routed underneath correctly, a 72xx will slide onto the posts without any problem. This means you are "in the ballpark" for mounting a 72xx without having to relocate the studs. If you have to relocate the studs on a Tune-o-Matic setup for a 7200 and its a flat top body, you can use the PL-8 coverage plate to surround the base and the relocated stud holes. No coverage plates are available for 7,8,9 and 10 string tremolos yet.

Flat mounting...

The other type of body is a flat top. It simply means the face of the guitar body is flat as a pancake. The The 72xx can fit on a flat top body as well, but only if it has a Tune-o-Matic, but if not, the 73xx is better suited. The versatile 7300 Series Hybrid is a perfect glove fit on most Strats (right) and can accommodate any flat top guitar....as  long as you have a flat area to mount it on. It allows for plenty of intonation travel room, radius matching and string spacing to make any guitar player happy. It has a low profile and is the bomb for palm muting. Several adapter plates are available for Fulcrum to Kahler adaptions, as well as other difficult retrofits. If you prefer, a 7330 Fixed bridge will also work on any flat surface. With no route needed, just screw it down and string 'er up. See installation guidelines for more info.

As in all Kahler tremolos you must route a 1" inch deep (not thru body) surface cavity into the top of the body to accommodate the springs underneath the trem. See Routing

Most basses have no routing under the bridge, so once its removed you have a nice fresh, flat area to install your new bass tremolo or fixed bass bridge. There are some clearance issues to hurdle first before getting excited about installing a bass tremolo. The 7410, 7415 or 7416 bass tremolos are meant for flat top basses only, but you need minimum clearance of 1.750" (1-3/4" inches ) from the intonation line to the back of the bass to use properly. (picture left) 7440, 7450 or 7460 Fixed bass bridges require no routing and can mount on any flat surface. They have 4-6 screw holes in the mounting plate that match up with most inline bass mounting holes, particularly Fender Precision and Fender Jazz basses and other basses styled after them. FREE Sizing templates