HI ALL I HAVE A PROBLEM WITH MY 1988 R20 2WD SUBURBAN, 454CI WITH TH400 AUTOBOX. I HAVE REPLACED THE SPEEDO HEAD, BUT STILL IT DOESNT WORK, THE CABLE IS IN
1ST CLASS CONDITION, SO I THINK MY PROBLEM IS THE DRIVE GEAR AT THE REAR OF THE GEARBOX, DOES ANYONE HAVE A WORKSHOP DIAGRAM OF THE TH400 THEY COULD EMAIL ME, OR MAYBE KNOW A SITE THAT SHOWS A TH400, THANKS VERY MUCH,