How do your parts buying practices compare to those of your peers? Results from FLEET OWNER's Aftermarket Monitor survey on diesel engines for 1996 showed that truck dealers were used as a source for engine brakes by 47% of respondents. In 1995 and 1994 the figures were 49% and 46%, respectively.

Engine specialists served as the source for 24% of engine brakes (up from 22% in 1995 and 17% in 1994), followed by jobbers/parts houses with 15%, and heavy-duty distributors with 9% of the market. Independent garages served as a source for 3% of engine brakes; local rebuilders 1%, and used parts 1%.

Although differences in sources for engine brakes were not observed when comparing one year to another, differences did appear when the data was segmented by variations in fleet composition.

Fleets composed primarily of heavy-duty vehicles used truck dealers and engine specialists as sources for engine brakes slightly more often than did medium- and light-duty fleets. Medium- and light-duty fleets, on the other hand, were more likely to use jobbers/parts houses and heavy-duty distributors as sources for engine brakes than were heavy-duty fleets.

The data for heavy-duty fleets was also analyzed in terms of new and used vehicles. Those fleets that buy 100% of their vehicles new were more likely to purchase engine brakes from truck dealers and engine specialists; fleets that buy 100% of their equipment used were more likely to use jobbers/parts houses and heavy-duty distributors as sources for engine brakes.

Analysis of the data indicates that these differences are substantial, particularly when looking at the tendency of the "100% used equipment" fleets to buy engine brakes from jobbers/parts houses and heavy-duty distributors, rather than from engine specialists.

The Aftermarket Monitor divides components into 15 major groups and sends out more than 4,000 questionnaires each month to commercial vehicle operators. Parts categories covered are diesel engines; gas engines; electrical and lights; air brakes, wheel seals and bearings; hydraulic brakes, wheel seals and bearings; manual transmissions and clutches; automatic transmissions; drive axles, universal joints and drivelines, and PTO drives; exhaust components and engine cooling systems; front suspension and shock absorbers; rear suspensions and springs; engine oil and filtration systems; tires; electronics, wheels and fifth wheels; seats, mirrors, tanks, and leak detection equipment; and paint.

For more information on FLEET OWNER's Aftermarket Monitor, call Tom Duncan at 914-287-6710.

The following individuals recently received prizes for participating in last month's survey: Eric Kramer, S.E. Johnson, Maumee, Ohio; James Stewart, Stewart's Wrecker Service, Orrington, Maine; Chris Campbell, Murfreesboro Pure Milk Co., Murfreesboro, Tenn.

The Aftermarket Report is a snapshot of information gathered each month as part of an ongoing research project known as FLEET OWNER's Aftermarket Monitor. It is intended to keep readers informed of important trends and new developments in the commercial-truck aftermarket.