The system used by Gillig from the mid 50s up to the early 1980s to determine the bus model number came from either the cubic inch displacement of the engine equipped, or its horsepower rating.

For example, if a Gillig which was built with the model number designation 855D, that means that the bus was equipped with a Cummins NHH-series engine, either the NHH250, NHHTC270, or NHHTC290. A 743D-series means that the bus was equipped with a Cummins NHH220.  The following list gives a breakdown of each model number produced, as well as the engine that it was most frequently equipped with.

318........................................................................................................Detroit Diesel 6V53 V6 diesel engine
501..............................................................................International harvester Corp. Inline-6 gasoline engine
534......................................................................................................Ford Motor Corp. V-8 gasoline engine
C-160/170/180/190....................................Cummins Engine Corp. Inline 6 rear vertical-mount diesel engine
743.......................................................Cummins Engine Corp. NHH220 Inline-6 horizontal-mount mid-engine
855..................................Cummins Engine Corp. NHH250/270/290/335 Inline-6 horizontal-mount mid-engine
636.........................................................................................Caterpillar 1160/3208-series V-8 diesel engine
555...............................................................................Cummins Engine Corp. rear-mount V-8 diesel engine
426......................................................................................Detriot Diesel 6N71 horizontal-mount mid-engine
590.............................................................................Hall-Scott inline-6 gasoline powered mid-mount engine
450...............................................................................International Harvester Red Diamond gasoline engine

Invariably, some situations will arise in which the model number will, for example, be a 318-series when the bus is equipped with a Caterpillar 3208. This is usually due to an engine replacement. Additionally, over 75% of all Gilligs manufactured by the Cummins VTF555 (also known as the triple Nickel) were subsequently equipped with the Caterpillar 3208 due to performance issues related to the VTF555-series engine.

On some models, a "C" or "D" will follow the model number, for instance 555D-13. This means that the bus was a type-D transit bus equipped with the Cummins VTF555 with 13 rows of 3x3 seating. A 501C-11 means that it is a type "C" conventional school bus equipped with an International inline-6 gasoline engine.

On some type D models, a "T" will be present in the model number. For instance, an 855DT-16 translates to a Gillig type "D" transit coach school bus with the "T" meaning that the bus is equipped with tandem rear axles, and the bus would have 16 rows of 3x3 seating.

More information concering the lingo can be read by clicking this link. It is provided by Jim Bramham.

The last Gillig model 743D-series was produced in 1972 as California was adopting stricter air quality regulations and new vehicle emissions standards. The 855D-series was brought into the lineup to replace it.

The very first rear-engine transit style school bus was a Gillig. Built in 1946, the first of these new buses was equipped with the Hall-Scott 450.

Washington State required all incoming school buses built after 1975 to be equipped with the new 8-way flasher system, becoming one of the first states to do so. As a result, most Gilligs from Washington State built after that year feature the 8-way system.

Gilligs have also been in various movies. In Dangerous Minds starring Michelle Pfeiffer. In the opening scenes of the movie, a series of Gilligs from Santa Monica Unified School District are seen. Additionally, Gilligs, and Crowns are seen in "Mr. Holland's Opus."

In the music video "American Woman" by Lenny Kravitz, a Gillig can be seen in the scene where actress Heather Graham is seen dancing on top of a white bus. The bus is an early 60s Gillig Conventional.

Gilligs tended to be the heaviest school buses ever built, with nearly 95% of the bus body being steel. Crowns used a mix of Steel and Aluminum, making their bodies lighter.

The color used on the background of the older oval-shaped Gillig Emblems is Ford Blue. Also, the emblems share similarites, except that on a Gillig oval there's a "v" shaped notch on the underside.

The side-mount radiator system used on mid-engined Gillig Transit Coaches and Crown Supercoaches was invented by the Embree family, for which a major transportation company in California is named for.

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From longtime GilligCoaches.NET Contributor Tom Shafer of California:

Gillig put Hall-Scott 504s starting about 1950, 590s starting with their introduction about 1954 or 1955, and I believe some 190 series (also known as 779s, their cubic inch displacement) in their buses. There were some pre-war Gilligs that had Hall-Scotts, but the immediate post-war buses only had International 450's mounted in the rear. It looks like Gillig went to optional midship engines in the larger buses about 1950, according to a brochure that I copied from Phil Gardner in the late 80's.

Some of those post-war pushers also had a smaller 269 cubic inch International engine. I have some photos and I.D. tag info on these. The 2 that I have found are '47 and '49, respectively, and both are smaller buses.

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There are some other models that you can add. In about 1950, Gillig started the small, flat roofed pusher buses with a 337 cubic inch Ford engine. I have a batch of photos of one of these, which I photographed in detail 2 years ago outside Fresno, including getting the serial number. There was no engine. I also took photos of a similar one in a closed yard in Earlimart last week, but no one was around to give me access. The yard has been closed for several yrs. I would love to get the info before the roof collapses due to extreme rust.

There appear to be some other small buses, perhaps on full Ford chassis, built maybe before or after the war. Crown was a Ford bus distributor and sold some Ford pusher chassis. The 5 lug wheels are usually a giveaway on this. See Don Wood's bus book for a shot of a Matson Lines Gillig transit bus.

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The "C" series is not limited to pushers - it includes midships as well. I think the "C" is a model designation, not standing for Cummins. "D" came in about 1964, but there was no major change in body until 1966. "E" came in in about late 1970. I haven't been able to find anyone to explain this to me.