Odd Prop I picked up today,any ideas?

[ladysuz]

Hiya,I picked up a prop today at a car boot sale,no idea what it is but am hoping someone can help me.

It is 5 feet in length
It has 6 bolt holes
1 inch bore
markings are :
13R01S
60 51
NP
12 87

all stamped on the boss.
any ideas?