radiomike7

Never seen that type of compensator used on a tandem rear, the usual way was a simple rocking beam between the springs. It looks like the chassis brace was extended to catch the springs if the chain failed. Either way was not a great success as linking the rear of one spring to the front of another forms a reactive system that transfers weight from one axle to the other under acceleration and braking.

Did it belong to Dawson or is it just in their livery, they are still in business and may have some information about it?

I think it might be this one.

It is a Kenworth cabover that belonged to a recovery company in Bristol.

Checker plate is a generic name for an embossed non slip plate, the OP required a certain pattern called diamond rather than the more common 5 bar.

Correct, still available if you do an online search.

Like this?

Good point but it would have been necessary to clamp against a mandrel exactly the same diameter as the half shaft.

Does it have a speedometer or a tachograph?

That's the one you had originally which worked.

That's a heavy duty box from a motorised scraper and with straight cut gears would make quite a din. What are you trying to achieve?

That would have been a Ford 'D' series, possibly with an alternative gearbox or having the diff turned through 180 degrees.

There has been an AEC LD55 on E bay for quite some time: https://www.ebay.co.uk/itm/AEC-Dump-truck-scammell-LD55-quarry-lorry/292857562079?hash=item442fabc3df:g:25oAAOSwEJ1cDNen Chassis numbers DN099>539 were AV690 built at Aveling Barford, BHV10001>10355 were built by Thornycroft at Basingstoke while WHV10400>10731 were built by Scammell at Watford including the later mk2.