There were several variations of split t-cases available in our wagons over the ten years they were made. Some of these differences were important, others not so much. The most important one is determining whether a particular case will fit in your rig. And this in turn is determined by what tranny is in your rig. Because Toyota not only used more than one t-case variation they also used different configurations of the same tranny. Also worth mentioning is that there is no difference between the t-case for a diesel and the one for a gas rig. Same splitcase used for both.
Determining what configuration of tranny you have is easy. Just look for a spacer between the t-case and tranny. This thing is about 3.5 inches long and very obvious. If you don’t have one, you have the early H41 or H42. The first picture is the early (1982) H42 out of my diesel. It’s easy to see that the t-case is bolted directly to the tranny housing. If you have a four speed with the spacer, you have the later or newer model t-case. H55’s are identical to spacer style trannys but in their case the spacer is the part of the case that contains 5th gear. Spacer style 4 speeds, H55’s and autos all use the newer style of t-case. The second picture is my H55 bolted to the front half of a late model t-case out of a 62. The spacer is clearly visible between the tranny and t-case housing. A spacer style 4 speed will look identical to this.
Why this is important comes when you attach a t-case. The bearing configuration on the back of the tranny and other differences determines just what t-case will fit on your tranny. The bearing on an older non spacer tranny projects very little from the tranny while the bearing on a newer tranny or the auto protrudes much further into the t-case. The other differences I will get to shortly.
Once you tear down both styles of t-case this becomes readily apparent. Could you determine this by serial numbers? Yes but this visual check will tell you the same thing with a lot less confusion. And you really don’t want to try to read the serial number off a newer t-case while it is still in a rig, it’s up on top next to the breather vent.
Just what are the other differences. One is the size of the intermediate shaft. Older t-cases use a 34mm shaft while the newer ones switched over to a larger 38mm shaft. This happened in April of 1985 if I heard correctly. Another is gear ratio’s of the t-cases and these are much harder to determine, short of counting teeth and doing the math. For the most part you will only find a 2.27 or 2.29 low range but there are exceptions. And ratio’s have more to do with how the rig performs than how it bolts together.
Manufacture dates may be of more help in determining ratio’s. Or knowing what rig the t-case came out of, for example auto’s had a low range in the t-case of 2.29 (4/86-1/90). US market 60’s used a 2.27 low range (8/80-4/86) and you will find some Canadian rigs that have a low range of only 1.9 (non US models), mostly I do believe these were installed behind early H55’s. Which appeared in Canada as early as 1983 while spacer style trannys didn’t appear until approximately 1985 in the US. And I have to admit I am not sure what ratio low range was installed in the spacer style 4 speeds that were sold in the US market from 85 to 87 but it should be a 2.27 low.
H55’s require a small plastic oiler for lubrication of 5th gear. The provision for this oiler is cast into the mounting surface of the t-case. You won’t find it on the early t-cases (80-82), but surprisingly you will find it on the t-case out of a 62 that has the auto tranny. At least mine did. I also recently found the oiler provision on an 83 tcase I recently took apart. In the picture you can see the notch for the oiler directly below the seal for the output shaft.
What does all this mean? An early t-case (with a build date as late as 10/82) will not properly bolt to an H55 or a spacer style 4 speed. The bearing configuration will prevent it from bolting on correctly. The machining of the front half of the t-case is too shallow for the bearing on a late model spacer style tranny.. Don’t do it or try to.
Can you put a newer case on an older non spacer tranny? In a word, yes. But there is an important part to include or it wont work. Sometime around the end of 1982 toyota started using newer style tcases on older non spacer tranny’s. But in order to do this they included a spacer to account for the different amounts the bearings protrude on the two configurations of tranny’s. You can see the spacer in the pic. This small spacer is not needed when mounting a late model tcase to a spacer style tranny and is not found on early (80-82)tcases either. The picture is of a tcase set up with a build date of 11/82 mounted to an early non spacer four speed.
Bottom line, if you have an early tranny you can use an early t-case or a later tcase as long as you have the spacer on the front side of the transfer gear and on a late model tranny you have to use the newer style of t-case. No if’s, and’s or but’s about it.
