The 1965 prototype chassis 906-016 with Eugen Kolb designed long tail was first time publically shown at the Le Mans test day in April 1966. Three 906 attended the 1966 Le Mans test day, two others with short tails. The 906-016 was not used in the actual Le Mans race (was later equipped with short tail and sold to private driver). After the 906-016 prototype, three 906 LH were made, chassis numbers 906-151, -152 and -153. While the 906 K weighed around 675 kg/1488 lb, the 906 LH with its longer nose and very long tail weighed 710 kg/1565 lb (35 kg/77 lb more). The longtail 906s were called as 906 LH (Langheck, long tail in German), while they could also be called as 906 LM as they were made for Le Mans.

The 906 LH was capable of achieving 174 mph/280 km/h with its 2-litre engine (906 K: 165 mph/265 km/h). At high speed the long tail started to create lift (opposite to downforce), which made the car go fast on the straight, but was dangerous to drive.

The 1966 Le Mans was a success for Porsche 906. Of course the podium places were taken by 7-litre GT40s, but then came 2-litre Porsches:
4. 906 LH #30 (906-153) Jo Siffert/Colin Davis (winner of 2-litre prototype class)
5. 906 LH #31 (906-151) Hans Herrmann/Herbert Linge
6. 906 LH #32 (906-152) Udo Schütz/Peter de Klerk
7. 906 K #58 Günther Klass/Rolf Stommelen 

The 906 LHs with their experimental bodies competed in the 2-litre prototype class. In addition to 3 Porsches, there were 3 Matras and 3 Ferraris in this class, but only the Porsches came over the finishing line.

The three 906 LHs that took the 2-litre prototype class podium at the Le Mans 24h, also took the podium on August 14, 1966 at the Hockenheim GP. This race saw 11 Carrera 6 out of 21 cars. It was basically a 906 race as the other cars were not of the same level.

The 906-151 was privately entered at the 1967 Daytona 24, but had an accident and fire. The 906-153 ran 15 races in 1967 season driven by Dieter Spoerry and Rico Steinemann. The 906-153 was used also with the short-tail body.