Now onto the Brabham kit. This was basically an extra 150CD carburettor for your SL90 engine. So you then had twin 150CD on a special inlet manifold along with the slightly different throttle linkage.
Additional items could be a set of stripes for the car, a wooden steering wheel or gear knob, a tacho, wider 12" steel wheels, a gas flowed cylinder head, a slightly hairy camshaft or a straight through exhaust system.
So depending on the size of your pocket, meant what extra parts you could afford to buy. Most Brabhams had just the carburettors and stripes, with a few exceptions having the steering wheel, gear knob and tacho too.
The kits I can only assume were sold until the end of the HB Viva's life September 1971. The kit was never offered as part of the new HC Viva range. So allowing for kits to be sold until the dealer's ran out, the last kit would have been sold by the end of 1972, if not well before. Total number of kits sold is unknown, but less than 200 I would think. So in my book a person converting an SL90, after say 1972, would be producing a PLASTIC Brabham, or replica Brabham.

So how can you prove the authenticity of the Brabham you are about to purchase for say £3,000? In a nut-shell you can't. Original owners probably never informed DVLA and nor did the Dealers. Some owners may have had the details changed, but as it was more cosmetic, rather than body types, DVLA might not have been interested.

Does anyone out there have a Registration Form with the word Brabham on it? The only people at the time who would want to know about the conversion were the Insurance Companies. So old insurance documents would be one way, or the bill of sale from the Dealership for work carried out, to prove the cars authenticity. Purchasing a kit over the counter is one thing, but it could be fitted to 5 or 6 cars over the last 40 years. So that bill of sale for over the counter purchase is open to abuse.

Brabhams have been appearing since the 1980s, in all different guises with a few definite PLASTIC ones being made up.
People around that time started to restore Brabhams, but the problem was the stripes. With Vivas, the front wings always needed replacing, hence the need for a new stripe. One chap who was restoring two genuine cars during the 80's had 20 sets of stripes made up, 10 black and 10 white. (Either that or 40 sets.) It depends on the colour of your car, to which set of stripes you used.
Light coloured cars had black stripes, while dark cars used the white stripes. The outer edge colour of the stripe denotes its 'White' or 'Black' tag. This chaps cars were never restored, in fact I think they were scrapped and the new stripe sets were sold on in bulk.