I installed the K48RE kit in my 2007. I found that step #3, the .055" hole drilled through the valve body, caused too harsh of a 1-2 shift and the 3-4 shift felt like it was going to brake the trans case. The 2-3 would take too long to release the 2nd gear band when it was in 3rd causing the rear end to clunk under light throttle. I drilled the hole out to .057" and installed a .056" cotter pin.
The cotter pin was a snug fit. Rounded head of pin is in the bore and clears the valve head. Make sure you fold the ends down on the outside of the valve body casing tight to restrict movement of the cotter pin. Cotter pin available at Hardware store. The cotter pin allows a very
small loss of fluid when the fluid is over 150*f, and almost no loss of fluid out the hole when the fluid is cold. Shifts are firm when hot and normally slushy when cold. In step #5 it talks about the check balls. Some vb
have 5 .250" check balls and some vb
have 6 .250 check balls. If your valve body has 6, install them all back where they came from.
The 6th ball fits in the oval passage top middle of pic. If your vb
only had 5 .250" check balls, don't worry about the #6 check ball. Drill all holes in plate from the check ball side to keep burrs from damaging the check balls. Always check for burrs after drilling.
In step #8 think very carefully about the future mods of your trans. You can't un-drill a hole. If a triple disk tc is in your future, or you have had no issues with tc lockup, do not
drill hole "C". If the check ball is missing from the passage under hole "A" do not
drill out hole "A". This is the rear band engagement passage. No check ball = harsh engagement (snow plow prep vb
). Drilling out the passage makes it worse. Do not forget the steel check ball in step #10.
Steps 13, REPLACE
accumulator with new aluminum replacement, Sonnax #22841-04K and front band servo with Sonnax #22301B-01K super servo and #22827-01 servo piston cover kit. Use all seals and rings that come with the accumulator and servo, Do not
use the rings from the shift kit. Don't forget to install the "O" ring in the new servo cover. Install springs from shift kit as directed. A new 3-4 accumulator spring will help the up shift with out the harsh bang. Sonnax #12861-01.
Front band strut #22825-01 is needed. Make sure hump is away from band.
I also installed a BD Diesel gov solenoid and sensor kit with their pan. Installed a slip in kevlar front band. Trans is shifting firm but not harsh. Matches up well with the new BBI injectors and Banks economind tuner.