More general info? Year, Model, 4x4 or 2wd, Auto or Manual. Also true final ratio has to include tire size.
Enter VIN and check under the Diff. this is a puseudo build sheet on your truck.
http://www.toyodiy.com/parts/q.html

Or
Look at the door jam area should be a code on the lower right hand corner of the sticker:

https://www.tacomaworld.com/threads/gear-ratio-confirmation-04-dc-4x4-trd-or.304549/
First digit:

• A = 7.5" ring gear
• B = 8" ring gear

Next two digits:

• 01 = 3:42
• 02 = 3:58
• 03 = 4:10
• 04 = 4:56
• 05 = 3:15
• 06 = 3:91
• 07 = 4.30

Last digit:

• A = 2 Pinion, Open
• B = 4 Pinion, Open
• C = 2 Pinion OEM Limited Slip

Or
Jack upthe truck and in neutral count the number of rotations of the drive-shaft for peer a full rotation of a tire. I.E drive-shaft turns a touch over 4 times per full rotation of the tire is most likely a 4.10 diff gear ratio, this does not give the effective ratio since the tire and transmission final drive ratio is included which is what you see in the rpm/mph indicated. For intance the 5 th gear in the manual transmission is .83 over drive.

 

93 T100 SR5 4x4 31x10.5R15 Tire’s
Code I see on label is A05A/A340F So I’m guessing 3:15 Rear End?
Tried to post pic of label and truck but I can never do it, even followed instructions posted on forum, maybe I can’t on iPad?

 

Do you know if the truck has been modified? Is there a lift kit installed? Bigger than stock tires?

 

Label says tires should be 235/75-15 could this be a problem as these tires are smaller than what’s on truck.

 

Nope! Taller tire ( the current tires on the truck) equals a lower rpm . The factory tire is just over 2 " shorter ( Shorter means higher rpms) than the tires on it now.. Using your numbers and a guessed rear ratio of 3.15, your rpms at 60 would only jump to around 1550 .
https://www.crawlpedia.com/calculators.htm
https://tiresize.com/height-calculator/

 

These are the ratios I show fer the stock ring gear fer the 1993 T-100 4WD.
Rear Axle, (6 cylinder), 4x4, ABS, 4.46 ratio (MT)
Rear Axle, (6 cylinder), 4x4, ABS, 4.70 ratio
Rear Axle, (6 cylinder), 4x4, ABS, 4.90 ratio (AT)

 

These are the ratios I show fer the stock ring gear fer the 1993 T-100 4WD.
Rear Axle, (6 cylinder), 4x4, ABS, 4.46 ratio (MT)
Rear Axle, (6 cylinder), 4x4, ABS, 4.70 ratio
Rear Axle, (6 cylinder), 4x4, ABS, 4.90 ratio (AT)

Even with the 4.90 with your choice of the current tires or going back down to stock, RPM's at 60 would be near 2200 not 3k.

 

Just out of curiosity, (if you have an automatic transmission) is yer O/D button pressed in? Is the O/D light lit on yer instrument panel? It's possible that the previous owner may have removed the bulb so you can't tell. It's also possible that yer OD clutch could be burnt/worn and not allowing the transmission to lock up. Does yer AT Temp light come on or is it lit?

 

Yes it is automatic and O/D button and light works perfect, AT Temp light never comes on.

 

Can you tell when it shifts through all 4 gears? O/D won't engage unless yer over 51mph and not going up a hill.

Could you safely shoot some video and post it? Thanks!

 

Hey i just got a 95 t100 and I’m trying to learn everything about it. My question is how do you know the O/D doesn’t kick in till 51 mph? And is the computer really that smart to distinguish when ur going up a hill? Thanks!

 

I think so.
I will try tomorrow , but I’m still having problems posting. I really wanted everyone to see the truck.

 

Actually I noticed the rpm’s jump around a lot. They can be at 2K and if I just touch the accelerator a bit it jumps up to 3K.
I will try and show it in video.

 

Actually I noticed the rpm’s jump around a lot. They can be at 2K and if I just touch the accelerator a bit it jumps up to 3K.
I will try and show it in video.

Check all the groud wires in the engine bay.I think you'll find one going to one of the fenders that if corroded or loose can cause a jumpy tach.

 

It's starting to sound like yer torque converter isn't locking up like it's supposed to. I'm guessing the torque converter is worn or damaged.
https://www.motor.com/magazine-summary/torque-converter-lock-may-1999/

I made a run tonight just to confirm the RPMs compared to speed. With the O/D button out and the indicator lit, the RPMs were close to 3000 rpms at 60mph. My differential ratio is 3.91:1 on my 2WD T-100 auto Xtra cab with the 5vzfe V6 engine. With the O/D button pressed in, my RPMs were close to 2000 rpms at 60mph.

 

BTW, how good is yer ATF? Is it brown/black or smells burnt? If it is, yer gonna need to replace the fluid with new Dexron III equivalent ATF.

Is the ATF at the correct fluid level? Do you know how to check the level? The ATF level should be checked with the vehicle on a level surface and the engine running. Shift through all the gears and put the transmission into Park. Set the parking brake. Pull the dipstick and wipe it off. Reinsert the dipstick back in all the way and pull it back out. The reading should be in between the HOT marks on the dipstick. If it's too low, yer gonna need to add some Dexron III equivalent ATF until the level is correct.

 

Sorry been busy for awhile and haven’t been on here, yes I know how to check fluids it looks clean and new. Previous owner was meticulous about truck, every maintenance done in the book at the dealer.
I did check the diff by jacking it up and rotating tire and count revolutions of driveshaft. From what I see it has a 4:88 gear ratio. Not what it says on label inside door 3:15.
What does this mean, was rear end changed? I can’t see the previous owner getting this done.

 

Finally got some pics posted.