When purchasing the piping for your drain/waste overflow, its important to know the size/measurements you're looking for. The old drain lines had a 1 3/8" diameter - all new lines will be 1 1/2". We carry drains that fit both. Our drain from the middle of the tub shoe to the middle of the "T" pipe (refer to the picture below - all straight lines are connected to one T-shaped pipe, which is our reference here) is 10 inches and from the middle of the over flow plate (the screw hole ) to the middle of the "T" pipe is 17 Inches. The new style drain is 13 1/2" from the "T" pipe, drain is 7" from the "T" pipe The new style will fit most of the old and new but with the new fiberglass tubs the holes can be cut on site which confuses everything. All of our 1 3/8 drains come with a 1 3/8 x 1 1/2 chrome plated slip joint nut and washer so they can be use on both the new style and old. This will save you a lot of time looking for one if you need it.
 Our suggestion is measure your tub to find out what your needs are. When measuring, make sure your measurements are straight and do NOT follow the curve of the tub (the drain lines are straight). The drain is exposed on the outside of the tub, so measure from the waste overflow hole (hole beneath where the faucet will sit) to the bottom of the tub (this measurement should be AT LEAST how long the waste overflow pipe measures from the overflow face plate to the "T" pipe) and from the drain hole to the edge (this measurement should be AT LEAST how long the tub shoe measures to the "T" pipe). If in doubt, call a plumber. Once it is cut;  IT IS CUT  there is no putting it back together.