Converting 2wd 4L80-E/85E to be used with NP208/NP241C

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,008
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
I'm copying this post off of FB where a guy did a good job of laying this out. Big deal to remember is, it'll have to be a full spline output shaft 2wd unit. Meaning the splines don't start at the end then stop about about 4 inches, but they go the whole length of the output shaft.


2x4 4l80e to 4x4 4l80e conversion with an np208 tcase is done...

THINGS NEEDED...

1 Fully Splined 2x4 4l80e transmission.

1 NP208 Transfer Case.

1 ACDelco 15724745 Transfer Case Adapter.
Amazon.com $70.83

1 Transfer Case Gasket O Ring Seal 4L60E 700R4 4L80E 4L85E 4x4 GM Transmission.
Ebay.com $12.95

1 ACDelco 9427692 Pressure Regulator Valve Bore Plug.
Rockauto.com $4.45

Parts only total $88.23

First of all go watch the videos at www.youtube.com/lonniesgarage
You won't regret it!

Video part 1. https://www.youtube.com/watch?v=9qCv8DILht4&t=4s

Video part 2. https://www.youtube.com/watch?v=6hwJPSb_bPA&t=90s

How To.....

1St... Remove tail shaft housing from transmission.

2nd... Install adapter (ACDelco 15724745) and mark flush on tailshaft.

3rd... Remove adapter plate (ACDelco 15724745) and cut tailshaft. (I cut 3 1/4" off as shown in pictures)

4th... Remove rear tailshaft bearing oiler and install freeze plug (ACDelco 9427692)

5th... Install the round rubber o ring gasket (This will be in the gasket kit) to the adapter (ACDelco 15724745) and install adapter to rear of transmission.

6th... Install paper gasket (from gasket kit) onto rear side of adapter plate (ACDelco 15724745)

7th... Install NP208 Transfer Case.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,008
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
The other good news about this swap, using the Tcase adapter he's listed, like the 80's Trucks, the adapter makes up the difference in length so he was able to use the same trans mount and driveshafts.
 

Forum statistics

Threads
42,058
Posts
908,211
Members
33,539
Latest member
Chuchito
Top