No.102 in the yard at Whitehead in 2005. Photo by B Pickup.

The Society owns two mainline diesel locomotives at Whitehead, known as "the Hunslets".

The 101 Class of Northern Ireland Railways were three mainline diesel-electric locomotives designed for use hauling the Enterprise passenger services between Belfast and Dublin. They were built, under contract from Hunslet Engine Company by British Rail Engineering Limited (BREL), Doncaster in 1970. They were of Bo-Bo wheel arrangement and fitted with 1350hp engines. All three were named, using names previously carried by the Great Northern Railway (Ireland) Class V locomotives, as follows:

No.  Name
101  Eagle
102  Falcon
103  Merlin

They were displaced from the principal passenger workings by the arrival of the 111 Class locomotives and were then used on freight duties. All three locomotives have since been withdrawn from service, the first having been stored in 1989 (103) and the last in 1998 (102). It was expected that 102 would be re-instated in 2002, but after only one outing it was stopped once more. 103 was scrapped in 1997, but 101 and 102 are now stored at the Railway Preservations Society of Ireland site at Whitehead.
(Sourced from Answers.com)

The NIR Photos website gives the following vital statistics of locomotive detail and final operation dates.

There are quite a few photographs available from the Irish Railway News website.

There is a discussion forum also for those interested in 102.
 

No.102 shunting fertiliser wagons at Adelaide Freight yard.  Photo courtesy L. Smyth No.102 on passenger duties enters Lisburn.  Photo courtesy L. Smyth No.102 shunting cement wagons at Adelaide Freight yard.  Photo courtesy L. Smyth