"For Interceptor III and FF I:

Brakes:
Pads, Front,  Int III: Lockheed LUP 17 (Morris 1800/2200)
Pads, Int/ FF I , Dunlop calipers,  Front  & Rear, Girling 6DB704 (Rover
2000, Alfa Guilia 1600 TZ)

Seal kits for Girling master cyls.:
.875" Cyl: SP2485, 2220, 2693, 2415, 2769, 2683 (all these kits, while
differing in detail, contain the basic front and rear seals and the port
shut-off seal)

1" Cyl: SP2375, 2480 (Aston Martin, Bristol)

Rad fan and wiper motor brush kits: Lucas 54701528

Bonnet release cable: British Leyland 369961, 1973 Rover 2000.

Mark III ashtrays, front: Triumph Stag; rear, Jag 240/ 340.

Mark I front sidelight/flasher lens: 1970 Alfa Guilia super.

Mark II number plate lamps: 1963-4 FIAT 1500 saloon.

Bonnet and boot lights: Jaguar 3.8- 420.

Mark III froint sidelight/ flasher lens: MG Midget

Dip switch pedals: Ford Transit accelerator pedal.

Mark III headlamps & accessories: Cortina GT Mark III.

Universal Joints for ALL Interceptors and FFs: GKN U45/515371

FF front (??) ball joints: Quinten Hazel QSJ222 (Austin. Morris 1800)

Interceptor & FF track rod ends: Quinren Hazel QR1379 (BedfordCF Van)

Mark II/III Top ball joints: Quintel Hazel QSJ 527 (Jaguar)
Bottom: QSJ 221 RK (Jaguar)"

I hope that gives you some useful crossovers!  No apologies for typos!

Ray Whitley, C-V8 II 104/2308, JOC 1642, BATANS, Halifax, Nova Scotia.