Topic: R151F Tranny Into My '84: Questions

[wrenchtech]

I want to run an R151F in my 1984 SR5, Xcab, 4x4 truck. It has a stock 22R. Right now I'm pretty sure it is set up with a forward shifted transfercase, so both sticks are in the extension housing and they come up through the console on the floor of the truck pretty close to the radio area of the lower dashboard. How are the R151Fs set up? Are they also forward shifted "dual stick". I'm wondering if I can keep my console or if I will have to cut the floor.

Also I will need to either get a transfer case that is setup with a 23 spline input shaft or install a 23 spline input in a transfer case that currently has a 21 spline input. If I was to look for a used transfer case to install the 23 spline into I imagine it would be best to find another forward shifted model, is there any diference across the years , keeping in mind that I might install a set of Marlins 4.70 gears later?  I've been told that the 22Rs were all forward shifted while the 22REs were top shifted. -- Matt

[rocktoy74]

Been there, done that! I put a R151F Into my 84' you will have to trim the floor just a little bit as they are not the exact same dimensions as the G52 that you currently have In your truck. Your rubber shifter boot will not fit properly either when you are done. I also had the matching transfer case and Installed a Marlin 4.70 gearset It Is sweet! I say go for It! About the only bad thing I can say about the setup Is you will miss your stock lowrange and find yourself In 3rd gear for most trail work. I plan to go dual cases as soon as I can afford It to get my stock lowrange back.Do It like I did and save the stock 23 spline Input gear for your dual cases as you will get a new Marlin Total spline Input with your 4.70 gearset. Oh yeah one more thing you will have to swap the shift forks to go dual cases because you really want the 4.70's In the rear case which would be forward shift as you mentioned. So In theory transmission-stock 2.28 forward shift crawl box-4.70 Marlin top shift transfer case. Hope I did'nt confuse you and It helped answer your questions.      

[wrenchtech [OP]]

...you will have to trim the floor just a little bit as they are not the exact same dimensions as the G52 that you currently have In your truck.

How much is a little bit? And does this mean I my console wont work either?  If not, maybe a console from a later truck would work?

Your rubber shifter boot will not fit properly either when you are done.   

Sounds like I'll need to find the correct boot and possibly do some welding     to get the hole in the floor shaped up right.  -- Matt

[TOYJOETA]

  I am in the process of buying, and putting a R151 in my 85, but I have a w56, will i have to trim anything to make it fit or will it bolt right in if i get the 23 spline t-case?  Also what will I have to do down the road when I have the money to put in the dual ultimate set up in, just buy the adapter and 4.7 gear set or would I be better off trading in my old T-case for one from marlin that already has the 4.7's in it.  because I don't have any way to clearance the housing.

[wrenchtech [OP]]

  I am in the process of buying, and putting a R151 in my 85, but I have a w56, will i have to trim anything to make it fit...

I believe that Marlin himself told me that the G series trannys that came with the 22r carbed motor are the closest shifter configuration to the R151 in the second generation trucks. I think the W's that I've seen from that period have everything a little farther back. The shifters on my G tranny '84 are far forward on the tranny hump. When I shift into first my nuckles almost hit the dash by the radio. 

Why are you interested in the R151? Ratios or beef?

Also what will I have to do down the road when I have the money to put in the dual ultimate set up in, just buy the adapter and 4.7 gear set or would I be better off trading in my old T-case for one from marlin that already has the 4.7's in it.  because I don't have any way to clearance the housing.

Marlin's got a couple of pages on the marlincrawler website where he shows the step by step for the 4.70 gear install. If you haven't already seen it check it out. -- Matt

Marlin's transfer  case gear install pages

[rocktoy74]

How much is a little bit? And does this mean I my console wont work either?  If not, maybe a console from a later truck would work?


Sounds like I'll need to find the correct boot and possibly do some welding     to get the hole in the floor shaped up right.  -- Matt

I will look at my truck today If I remember correctly It was not much and I was still able to use my plastic console but It Is not a SR5 truck so It's really just a piece of plastic. I think you could make It look factory with a little welding and shaping.

[rocktoy74]

I believe that Marlin himself told me that the G series trannys that came with the 22r carbed motor are the closest shifter configuration to the R151 in the second generation trucks. I think the W's that I've seen from that period have everything a little farther back. The shifters on my G tranny '84 are far forward on the tranny hump. When I shift into first my nuckles almost hit the dash by the radio. 

Why are you interested in the R151? Ratios or beef?


Marlin's got a couple of pages on the marlincrawler website where he shows the step by step for the 4.70 gear install. If you haven't already seen it check it out. -- Matt

Marlin's transfer  case gear install pages

I think you are  right about the shifter configuration the G series and the R series are pretty close.