From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Specification list noting Lockheed Jacks, the position of a spare wheel, and the axle ratio.
| Identifier | ExFiles\Box 92\6\ scan0037 | |
| Date | 20th October 1930 | |
| -7- Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}14/KW.20.10.30. Lockheed Jacks. One Spare wheel on off side. 8.33 axle ratio. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||