Hi Winger,
What you have is the first version of the RC10 - it has the short front wishbones/arms & what we call the '6 gear' gearbox (later cars had a gearbox called the 'Stealth' which was simpler, more efficient & allowed the use of a slipper clutch to tame wheelspin/wheelies)
The version of your car came in a number of specs with different kit numbers;
'6000 basic kit, less all electrical
6010 full kit, less battery
6012 full kit, less battery, body, wing
6016 full kit, ball bearings, less battery
6020 full kit, with 6-cell battery pack'
The above information came from Slotcarrot's very informative thread here;
http://www.rc10talk.com/viewtopic.php?f=35&t=13059
The shell on your car is the alternative 'Sidewinder' body - the body shown on your scanned image is the Protech1 shell that you can still buy & would have been originally supplied with the kit (if the kit included a shell)
You will hear people talk about Caddilac & Edinger cars - this relates to the street name/location of the factory - earlier cars were made at the Edinger address until they switched production to Associated's Caddilac address. The same basic RC10 was made during this time at both places but early production cars assembled in the Edinger factory featured a number of significant differences that makes them more desirable & valuable to some collectors.
With you speed problem - its most likely that your batteries are well passed their sell-by-date - you can still get battery packs made up from the subC type battery cells that will fit straight in your car - these will be the 'Nimh' type (Nickel Metal Hydride) rather than being the older Nickel Cadnium (NiCads) that your old batteries will be. The Nimh batteries are redily available & reasonably priced, but you will need a Nimh specific charger due to the different charging characteristics of these batteries. Your motors could also probably do with a good clean too, and new brushes if you can find them, as these are probably well worn - ideally you'd skim the commutator of the motor on a dedicated lathe (This is a process that trues the contacts on the centre part of the motor & stops the brushes bouncing that causes arcing) But finding someone with one of these lathes that offers the service these days is likely to be very slim!
Oh, and the connector on the new pack is the wring one, so it will not plug into ESC on RC10.
