Turning a R155F into a R156F (Yes I've Searched)

So I currently have a R155F, and from what I've read the parts should be some what swappable from the 155 to the 156,

Has anyone tried to upgrade?

I pulled parts numbers, from the 156 and 155, the parts for 3rd,4th and Reverse all look to be the same, so I am thinking if I am doing a full rebuild of this trans could the 156 gears for 1,2,5 work in the 155 case? And if they should work, what other parts will I need. And before someone says it, why not buy a 156 - my fear is swapping in a 156 is the future of the truck as the 156 is a bit of a unicorn and only came in the 16/17 and the 155 seems to share most parts with the older gens.

I know it might not be cheap, I know it breaks from tradition, I know I am going to be trolled, but I am here to learn, and I am here to ask a genuine question since I can not find it anywhere on the web.

 

Just curious, why do you want this? Besides the ratios and the first gear synchro, what are the differences? I'd imagine that is where you'd have to start.

 

That's pretty much it, the ratios and the 1st gear Synchro. 1st is always a bitch to get in to on mine, and always has been I had hope that the better synchro would fix that.

Is there a reason not to do it? are there better options?

 

Then why not consider exchanging just the synchro? I would look up the component dimensions and compare.

 

Toyota manuals are not impossible to DIY rebuild. You need a good snap ring plier and a simple gear puller, and patience with a lot of attention to detail. It's otherwise not hard. I've rebuild a 4L60E (gm automatic) and it was a lot of parts and was probably the most complex mechanical repair I've done. I recently rebuild a R150F ('00s Tacoma 5 speed) and it was easy, just a little more complex then a transfer case.

If it were me I would split the case and rebuild the synchro.

Amayama and Partsouq were great sources for parts

 

I am trying, I am not the best at reading the parts blow ups, How would I tell? And how do I know what PNis the one I need I see 2 sets of parts.

What I found:
155:
Synchronizer Ring #1 (#33367-35080) Previous Version(s) 33367-0K010;33367-0K100
Synchronizer Ring #2 (#33368-35080) Previous Version(s) 33368-0K010;33368-35050
Synchronizer Ring #2 (#33368-35090) Previous Version(s) 33368-0K060;33368-0K090;33368-35070

156:
Synchronizer Ring Set #1 (#33037-35030) Previous Version(s) 33037-0K050;33037-60020;33037-60040
Synchronizer Ring Set #1 (#33037-60050) Previous Version(s) 33037-0K010;33037-0K030;33037-0K060
Synchronizer Ring #2 (#33368-35090) Previous Version(s) 33368-0K060;33368-0K090;33368-35070
Synchronizer Ring #2 (#33368-35080) Previous Version(s) 33368-0K010;33368-35050

1st gear (33032-60111) Previous Version(s) 33032-0K021;33032-0K041;33032-0K071;33032-0K100;33032-22040;33032-60110
2nd gear (33033-60050) Previous Version(s) 33033-0K030;33033-26030
5th gear (33336-71040) Previous Version(s) 33336-71030;33336-71031

 

Yea I can barrow all the tools from my Father in law, He is a Steam and Boiler tech/engineer, that is deep in to old panhead Harleys and rebuilding them, I just have to gain the knowledge on my own for this trans, He has everything I could ever want in his shop, and every tool I would ever need, I just need to have the parts the the facts that it will go together and work at the end of the day.

 

Im also interested in this as well. The gap in the 1st-2nd on the R155f kills the sand performance once your in high range. The close ratio RA60F would be ideal with the if you could swap out the 1st for a higher one like the AX15. My application includes a 4spd atlas so the taller 1st of an AX15 in the R155/156F wouldnt bother me, Has anyone looked into that? That would make the r156F a wicked off road unit with some economy provisions included. Just for kicks I believe there could be some compatibility to most of these.

These are the ratios im coming up with for possible cross compatible trans combos.

Gear R156F - RA60F - R154 - R155F - AX15 ------ R156F(Ax15 1st/2nd/5th)
1st 4.17 ------ 4.31 ---- 3.25 --- 4.31 ---- 3.83 ------- 3.83 (4.17- 155f)
2nd 2.19 ----- 2.33 ---- 1.95 --- 2.33 ---- 2.33 ------- 2.33
3rd 1.49 ----- 1.44 ---- 1.34 --- 1.44 ---- 1.44 ------- 1.49
4th 1.19 ----- 1.00 ---- 1.00 ---1.00 ---- 1.00 -------- 1.19
5th 1.00 ----- 0.83 ---- 0.75 --- 0.83 ---- 0.79 ------- 1.00
6th 0.84 ----- 0.69 ---- N/A ---- N/A ----- N/A ------- 0.79
Rvr 4.00 ----- 4.22 ---- 3.02 --- 4.22 ---- 4.22 ------- 4.00

 

@BassAckwards did a swap.