I have a large collection of parts and I came across this slightly chewed, possibly Technic, part. No numbers on it, just the Lego on the studs. It's 15 Technic holes and then a T-piece on the end with 2 studs either side. The head seems to have a slot through it. Any ideas?
That’s a crane-arm centre. It’s usually used in non-Technic sets together with the crane-arm outside to obtain a telescopic arm, e.g., for cranes or firefighter ladder trucks. The slit at the end is to insert a piece of string for using it as a cable crane.
Here's a picture showing this piece in use as the boom of a crane from 4552: