Here's a new Timing Chain Kit for the following models from Triumph -

TRIUMPH

Triumph 2500 / 2.5 Saloon (1968- 77)

(Not 2000cc engines)

(As you can see this is a Duplex Chain).

Included in this kit it the following -

Timing Chain (Duplex)
Oil Seal for Timing Cover
Tensioner
Gasket for Timing Cover
 

You need this kit for any engine rebuild, the oil seal will have gone hard and the timing chain will have stretched making it noisey and more likely to break.