hope this helps, by the way all three point harness' have been banned for speed events
57.2.1. All vehicles must comply with K.2.1.2, K.3.1.2
(not plumbed in), K.5, K.6, K.8.
2.1. All seat safety belts must be must be complete
units sourced from a recognised manufacturer and
fitted in accordance with the manufacturers
instructions, MSA recommendations or FIA
requirements. (See FIA Drawing Nos. 253–42, 253–43,
253–44 and 253–45)
Seat belts, in the following specified configurations,
must be worn and be correctly adjusted at all times
during events:
2.1.1. Three point. One diagonal shoulder strap and
one lap strap, with three anchorage points on the
chassis/body shell or roll over bar of the vehicle on
either side and to the rear of the driver’s seat.
2.1.2. Four point. Two shoulder straps and one lap
strap, with four anchorage points on the chassis/body
shell or roll over bar of the vehicle. One either side of
the driver and two to the rear of the driver’s seat.
2.1.3. Six point. Two shoulder straps, one lap strap and
two straps between the legs, with six anchorage points
on the chassis/body shell or roll over bar of the vehicle.
One either side of the driver, two to the rear of the
driver’s seat (or one symmetrical for the two shoulder
straps) and two between the legs.
2.1.4. Where safety harnesses are mandatory it is
recommended that those described in 2.1.2. and 2.1.3.
are homologated by the FIA and carry their label.
2.1.5. It is permitted to make a hole in series production
seats to allow secure anchoring of seat belts.
2.1.6. All seat belts used on International events must
be homologated by the FIA, and carry their label.
2.1.7. It is not permitted to mix parts of seat belts. Only
complete sets as supplied by manufacturers should be
used.
2.1.8. Only one release mechanism is permitted on
each seat belt configuration and this must be available
for the wearer to operate whilst seated in the
competing position.
2.1.9. The anchorage points to the rear should be
positioned so that the strap from the shoulder is as
near horizontal as possible. It should not be located on
the floor directly behind the driver/co-driver.
2.1.10. Seat belts once involved in a serious accident
should be discarded as they are likely to have
stretched. Belts subjected to oil, acid or heat should be
replaced.