Not all D.B loaders will fit all models.
The loaders that fit specific models have 'designation' letters and numbers on the identification plate, situated normally on the left underside of the frame.
For example, LF7, where L denotes 'loader', F denotes 'front', and 7 denotes the model it is meant for, in this case the 770 & 780 series tractors. Similarly 8 for the 880 tractors and 9 for the 990, 995, 996 tractors. The 12 is for the 12 and 14 series from 1200 to 1412. The LF loaders were the standard duty, LH were heavy duty loaders. These loaders had single acting rams and the LS (super loader) were double acting.
When the 90 series tractors came in, some early ones would take the LF loaders but were soon dropped and replaced with the H type loaders, being the FD90, GD90 and HD90. The designation letters covered increasing robustness from FD (the standard loader), through GD (General Duty) to HD (Heavy Duty); these were all of the fixed frame type. T he QD (quick detach) then became available and when the tractor livery changed to red under the Case IH name, these QD loaders were re-numbered to L type, L1000, L1100, L1200 and L1500. The 1000etc denoted the lifting capacity (in kilograms). Early models of these loaders retained the single crowd ram for the fork and bucket and other front attachments; twin rams were introduced on the QD and HD loaders.
The Quick Detach loaders were quite different to the others in as that the oil pipe couplings were re-positioned and connected by means of a bank of quick release unions to a block of pipes that formed part of the loader bracket frame. Operation of the loader was by cables running from the base of this unit operating the spool valves, through the front of the cab to the quadrant mounted on the side of the instrument binnacle. Most of the other loaders used the same system as previous with oil pipes plumbed into the hydraulic system of the tractor, and actuated through the hydraulic lever locked in the 'select' position by means of a latch, and the oil feed diverted to the loader via the 3 way valve to the spool bank mounted beside the instrument panel. The system of external couplings was adopted because under HSE legislation it became illegal to have oil pipes exposed and running inside the cab. David Brown did supply a 'quick release' system for the attachment of bucket/fork etc, prior to this, a unit was made for these loaders by Slewtic.
Optional extra available for the loaders included a levelling bar which allowed the operator to keep two points of this item in parallel at any height of the loader, as well as a pallet fork assembly, bucket/fork quick release, and a loader stand (for removed loader).
One point to note when purchasing a loader is to look at the rams for rust pits and lumps in the chrome, as bad ones will cut out the seals. Also look at the seals for obvious oil leakage. The condition of the hoses should speak for themselves and look also at the wear on the pins on the brackets and the front ones as well, it's the holes that the pins fit through that wear mostly, the ram pins don't normally wear as much.
Thanks to Powerrabbit for this excellent summary.