Before 200 posts / questions get put up, in general the following applies to the WHOLE FAMILY of JBL 4" coil compression drivers....
(1) YES they are ALL interchangeable if you are experienced at doing this and can sweep test,clean,etc etc. Otherwise let a service dealer do it.
(2) The Phenolic models ( 2480/82/85/375HP ) and the OEM models sold to heath, RCA, Dukane, etc have wider mounting hole patterns and different gaps so NO you can't do it. And if it's a 375 being sold on ebay with a dukane model number that has a *P* on it, it's phenolic and NOT a "375" no matter what the seller says..
(3) The older alnico's have guide pins and SOMETIMES a given dia won't align in a given motor...again, have a service guy beat on it before you wreck yours. Murphys law is especially harsh here.
(3B ) YES there is only ONE correct position for a dia in *each* model driver so the lead wires and coilwire points fit. ( see #1 )
(4) The newer ferrites and Nd's have shoulder alignment with larger ( sometimes..?? ) gaps ( esp at the coilwire places ) so are easier BUT #3 can still haunt you.
(5) The dia for the 2452 is the stock 2450 with some small hardware / posts ( included ) that poke through the back cap.
(6) The $$$$ replacement dia for the 476 is identical to the 2450SL.. consumer/pro labeling. Don't let the ebay guys blow smoke...
(7) The diaphram on the 2453 is ATTACHED to the cap so most probably the replacement IS a new cap also...haven't seen one yet.
(8) Some coated types were NOT available in 16 ohm from PRO - maybe from consumer or by special order. For some reason the EU did??
And finally the nagging number FIASCO that JBL created with the 2450:
2450 = 2" exit driver with ribbed diaphram
2450SL = 1.5" driver with COATED, SMOOTH ( 2445 ) diaphram
2450SL-a = 1.5" driver with COATED, RIBBED ( 2450 ) diaphram