Just for information. A smaller German eBay site offers a Jaguar XK block for sale stamped E-6008-10. I know nothing about these blocks other than the E should stand for a C-type or D-type engine.
Following the “standard” Jaguar practice the 10 should indicate a 10:1 CR.
The above link shows other pics of this block, also showing an oil pump that I don’t recognize (but could be original to these “E” engine).
Bob K.
Something just doesn’t smell right, here: were ANY Cs or Ds 3.8 liter?
Per Wiki on the D type:
Engine displacement began at 3.4 litres, was enlarged to 3.8 L in 1957, and reduced to 3.0 L in 1958 when Le Mans rules limited engines for sports racing cars to that maximum.
Aha… thanks! Was not aware of that.
And the 3.8 was first done by a private company, can’t think who it was of the top of my head (the insulation went a few years ago)
Robin:
Alfred Momo of Briggs Cunningham’s operation was, I believe, the first to enlarge a block to 3.8 and it was fitted to their D-type XKD 507 in early 1957, This car is at the Revs Institute in Naples, Florida along with all the other Cunningham race cars.
Chris.
That sounds correct. Would have preferred it was a BRITSH company but hey what the heck 
Bob:
All C-types were 8:1 CR and all D-types were 9:1 CR, I am not aware of any of the factory cars having a 10:1 CR.
Chris.
The high number 6008 is suspect. I don’t see any other cars on here with a number in that range, the highest being E5033-9 in the Low Drag Coupe, and E5028-10 in the E-Type Prototype.
Was there a separate series of numbers for blocks in the C and D Types?
C-Types are E1001-8 on.
D-Types are E2001-9 on. A single E3005-9 and five E400x-9 are reported.
XKSS are E20xx-9
Lightweight E are RA13xx-x
Hmm… makes one wonder what this “rare” block really is?
EDIT: it seems to have been purchased, so it may have indeed been a genuine thing.
If there’s E1… E5 and this is E6… it’s likely not a fake (what for), and the number seems to be original plus the heater has not been drilled. Is that normal? Sounds like they were stamped for the cars they went in or by season, not as a proper manufacturing number. Are there records of engines without cars? Unless that was done on many blocks or this doesn’t look like anything special: New, exciting. Unrecorded. No?
it’s FOR SALE…caveat emptor
So far there is no evidence there were ever any E5000 series, let alone E6000 series.
Looking the list over more carefully, I see there were E3001-9 through E3005-9 in sequential cars, probably for the '55 LeMans team.
Neither the E1000 nor E2000 series seem to have got into 3 digits, i.e. less than 100 in each.
There ya go…
Doesn’t get any more rare than something they never made! 
It’s… none of a kind!
Letter stamping sets aren’t that hard to find.
Letters can be obliterated and re-stamped.
But one would think that in creating a fake you would use a legitimate number.
Maybe it was an LE from a 3.8 Mark 2 or NE from a 3.8 Mark IX?
But not with a 10 CR.
I suppose it could be a undocumented special prepared for some private racer in the 1960’s.
I also don’t recognize the oil pump. Could it have something to do with a dry sump setup?
more research required
factory definitely made 10-1 motors one example EE1207-10 a 3 litre block
there were several dozens maybe of E5000 motors
“E5033-9 in the Low Drag Coupe, and E5028-10 in the E-Type Prototype.”
I need to dig my records out of all the factory works motors to get a better idea of what there was
PS the first Jaguar 3.8 litre blocks were actually cast with 3.75 litres on side of block
The earliest big bore of 3.4 block probably phil hill USA
certainly Harry firth Australia turned out 3.6 plus motors by 1953 made the pistons himself at REPCO factory on a weekend
I have never had the good fortune to see one in person, but I believe that the scavenger pump and pressure pump in the D-type dry sump setup were driven by a transverse jack shaft, so yes, this would appear to be consistent with that.
