Mystery solved!!
Goto page 4, KMFDMk has a post with a bunch of active links and mirrors. But as soon as I find the time (or if Dean does it first), I'm going to update it with all the correct part numbers and more, because I, wait for it....... FINALLY SOLVED THIS FREAKIN MYSTERY!!
What the hell are you talking about Fiend, right? This one has been going on for years (almost a decade now?), read this whole thread if you want the history, but the problem we've always had with this calculator and the part numbers, is sometimes you get a gear combination that doesn't physically fit. The calculator has 2 part numbers for every speedo cable gear listed, and we didn't know why there were 2 sets originally. I solved that one back several years ago, turns out that every speedo cable gear is available in an 11 tooth AND a 10 tooth compatible version. I posted the correct part numbers differentiating between the speedo cable gears at that point in time. Then I tried to use this thing to correct my speedo, ordered the right speedo cable gear for the right #tooth output shaft gear, and it didn't fit! The 4.3 diff cars came with gears that were different diameters from all the others I had (I have a lot of trannies, including r154s). Well, the solution is rather obvious, I don't know why no one else hasn't figured this out before, but I recently removed an output shaft gear from a tranny and there was the answer staring me in the face. So I ripped a couple more out, and voila...
It makes perfect sense, gears usually change diameter to change ratios right? There is a range stamped right on the suckers that list which speedo cable gears they work with! So with a little help from Mark at McCord Vancouver and some digging on toyodiy.com, I have compiled this life saver of a list for us all...
Speedo Cable Gears
33403-29145 31 teeth (for 31:10)
33403-29125 32 teeth (for 32:10)
33403-29135 33 teeth (for 33:10)
33403-39075 34 teeth (for 34:10)
33403-19235 35 teeth (for 35:10) (MK2 with 4.3 diff)
33403-39495 28 teeth (for 28:11)
33403-39245 29 teeth (for 29:11)
33403-29105 30 teeth (for 30:11)
33403-19245 31 teeth (for 31:11)
33403-19255 32 teeth (for 32:11)
33403-29115 33 teeth (for 33:11)
Output Shaft Gears
33481-22030 10 tooth, fits 31-33
33481-14031 10 tooth, fits 34-36
33481-22020 11 tooth, fits 31-33
33481-14020 11 tooth, fits 28-30 (unconfirmed range in person, range not listed in epc)
Yeah that's right, I found part numbers for new gears we didn't know even existed! Toyota used this size of gears on several different series of trannies (any R or W series for sure), and a bunch of newer trucks introduced some new gears to our collective. We should be able to adjust for just about any rear end now.
So, instructions in clear English...
1: Use DeanFun's (Slip) calculator to figure out the most ideal speedo gear combination you need. FYI that thing is not mk2 specific! The important numbers in there are the diff gear ratios and the tire sizes, which you can select. Any car running an R or W series transmission, one of the rear end ratios in there and a Toyota gauge cluster will work (and I've tested that calculator on all the different cars my trannies are from, its predictions for what speedo gears should have been in them vs what was, has been spot on).
2: Decide if you are going 10 tooth or 11 (the calculator tells you the best match, but if you look in the Final Drive Calculations section it shows you the resulting ratio of the gear set you were suggested to run, and in some ranges there's a variant in the other output shaft gear size that's close enough and might just save you from changing out your output shaft gear.
3. Look up your Speedo Cable output shaft gear from the first 2 columns of part numbers above. eg if you settled on a 33 cable gear on a 11 tooth output shaft gear, you need the 33:11 speedo cable shaft gear.
4. Determine the compatible Output shaft gear from the last column above that matches your output shaft tooth count (11 or 10) and the range your speedo gear falls into. In the 33:11 case, you need "33481-22020 11 tooth, fits 31-33".
So the good news is this mystery is finally settled, and this shit works! I just had an 82 LType auto with the 4.1 in my shop, with 25inch tall tires fitted and I converted it to 5spd with a tranny out of an 82 that of course had gears to match a 3.72. Calculator told me I needed a 33:10, so I ordered both gears from Mark (they are cheap thru him btw), and the car has a rock solid speedo that is bang on now!
The bad news is, there are more output shaft gears then we initially thought, and most of us who have changed rear end ratios are going to have to change both gears. Also, I've been told that you can change the output shaft gear on Ws without removing the tailshaft if you have some long nose pliers, and that is not the case. Although with a lot of fiddling you can get the clip off, the gear will not slide past a flange in the tailshaft. Not sure if there's a similar issue on R series or not.
Note 1: about that "33481-14020 11 tooth, fits 28-30" output shaft gear. I do not have one of those here, they came on some of the later trucks and the EPCs do not list the range in the comments like they do for some. I have confirmed the 28-30 range speedo gears are of the same family as ours and this is the only output shaft gear listed for the vehicles that use those gears, so it must be correct, but I have not seen one in person to confirm.
Note 2: keen observers may have noticed that the 10 tooth output shaft gear that came on our 4.3 cars is stamped 34-36, but there is no 36 tooth speedo gear listed. This is the one remaining mystery, is there a 36:10 gear? Toyota's EPCs can be a pain to sift though to find stuff like this, you always have to look at parts for a specific model. I've spent a good hour+ on toyodiy.com trying to find this damn thing and no luck. If anyone comes across it, post the number and I will add it to the list. Would be handy for those running tiny diameter tires with 4.3 gears (like 275/35-15s, mmmm) or 4.88 rear ends or other such craziness (yes they exist).