Gun Powder Waggons
Additional notes from Travellers Guide (Blue cover):
Built ? at Boston Lodge for one of the firms supplying blasting powder to the quarries, probably Curtis's & Harvey; riveted body with double doors at one end. One of the very few private owner wagons to run over the FR Co.; has been used as a cement van. Was numbered 16 from early preservation days until 1967 when renumbered 152. It presently carries a fictitious livery but is similar in style to a livery just visible in one of the Bleasdale Photographs.
The Gun Powder Van was used at Boston Lodge to store sand for locomotives until late 2005 when it had to be withdrawn because the body sides, at the door end, had parted company with the floor and solebar. A survey showed that repairs would require the whole body to be removed from the underframe and that the lower part of the body and the angle connecting it to the underframe will have to be replaced.
Other similar Gunpowder vans still exist in the Blaenau Slate Qaurries, it is likely that they were all built at Boston Lodge as they are mostly mounted on standard Slate Wagon chassis. An example at Llechwedd Slate Quarry is mounted on a GWR slate wagon chassis.
 Second Gunpowder van - body only
In a 2011 article,  Dave High states that 'The Llechwedd waggon has no underframe and is of a different pattern to 152. Restoration requires the construction of a new underframe. This will be of new construction, using axle boxes ex-stock. It may require new wheelsets to be manufactured if it is similar 152 as the latter vehicle has longer-than-standard axles.'
According to Boyd, Gunpowder wagons had the same dimensions (apart from height) as 2-ton Slate wagons. A wagon of this type still exists in Llechwedd Quarry and is on display, although it is mounted on a GWR Slate wagon chassis.
This example from Oakeley is much larger than the FR Co.'s example. It is clear that it runs on a standard 3-ton slate wagon chassis.