Toyota has 2 main types of chassis codes. The older style from the 60's to the early 90's and the ones from then until now. Cars like the Corolla, Land Cruiser still use the older style codes because they are old cars, haha. They're pretty similar and it breaks down something like this:
A = Engine Family (These usually start at 1 and go up, 1A, 2A, 3A, 4A, etc.)
E = Chassis Family (E = Sprinter, Corolla, Scion xD, Auris, etc.)
8 = Major Chassis Revision
6 = Minor Chassis Definition
The last number will change based on either chassis differences or engine revision differences. For example on the AE86, since the SR5 and GT-S both share 4A engines they are both AE86's, but the 3A-powered version of the same car is an AE85. Similarly the 6th generation North American (1988-1992 Corolla) is an AE92 whether it is a sedan, coupe, SR5, GT-S, wagon, whatever because they all have 4A engines (be it a 4A-F, 4A-FE, or 4A-GE). The AE95 is the AE95 because it is AWD.
The AE91 (never sold in North America) is an AE92 with a 1.5L 5A-F engine instead of the 1.6L 4A-F. Toyota started using 2 letter engine families in the late 80's as well, so they started using codes like JZA70 (70-series A-chassis with a JZ-series engine).
The RA64 is a Celica with a solid rear axle and the RA65 is a Celica with IRS, even though they both have the 22R engine. (For that series of Celica all models with an even number are solid rear axle and all with odd are IRS.)
There are exceptions to these rules every now and then, but Toyota is pretty consistent with their naming.
Now getting onto the newer style of Toyota chassis naming, it is pretty similar, but they were running out of letters for the chassis family, so they added an extra letter to the codes. This letter is either C, S, or X (or N in the case of the Scion tC -- I think that may actually be another series of chassis codes Toyota is starting, but it's the only one so far).
C is used when the last letter of the engine family is a Z.
S is used when the last letter of the engine family is an R.
X is used when the engine family only has 1 letter.
Let's take a look at the RAV4, as it is a good example of all types being used:
1996-2000 RAV4: SXA10 = 10-series new-type A-chassis with an S-series engine
The A chassis code was previously used for the Carina FR, Celica FR, and Supra, but the next-gen A chassis code is only used on the RAV4 at this point. In 2001 the RAV4 got the 1AZ-FE engine and as such the code changed:
2001-2005 RAV4: ACA20 = 20-series new-type A-chassis with an AZ-series engine
Then in 2006 the RAV4 got an optional GR-series engine with the 2GR-FE:
2006-2008 RAV4 V6: GSA30 = 30-series new-type A-chassis with a GR-series engine
2006-2008 RAV4 I4: ACA30 = 30-series new-type A-chassis with an AZ-series engine
There aren't many models that still use the old-style chassis codes. The Corolla still does with the E chassis codes, the Land Cruiser still does, and Lexus has a few; namely the LX, GS, GX, LS, and SC.
Hope this answers some of your questions. Using Toyota chassis codes are sometimes better than simply using generations or years, because for example the 70-series Corolla in North America was only made until 1983 but in Europe/Japan it was still manufactured until 1987.
Also the last generation Corolla (9th) came out in Japan in 2000 but we didn't get a new generation until 2003 and we were 1 series ahead of them. (Japan was ZZE120 we were ZZE130).
Jeff
