Opening up a hydroboost output end to accept a 40MM master cylinder. Going to use this in combination with a spacer. Not bored full depth so the spider that holds the output rod will still be usable.
The GMC came with a cast 4.25" water pump impeller. This can be swapped to a replacement water pump. Replacements mostly have a stamped open back impeller of a smaller diameter.
Original 4.25" cast impeller compared to the generic 3.875" impeller
I set the clearance .015" minimum. Using a pump affinity calculator like-
Cruise control gave out in multiple ways... Foam filter deteriorated enough that the solenoid couldn't pull in, removed. Minimum speed switch went erratic so it got jumpered with a paper clip at the transducer. Stalk switch went out so it was replaced with a door bell button for engage and jumpered the hold part to always be on. Still turns off with the brake pedal. Love my auto throttle.
Glacier by Denali
On the way to Homer spit
Fish at homer spit
On the way to Stewart
Fellow GMC at Stewart...This coach was Darren Paget's who did stainless countertops
Norm Alinson present owner
Ferry to Dawson
Dawson
Dawson
Attempted window repair from rocks thrown by a nine axle truck. The window later cracked big and needed replaced
Lost a headlight too
Talkeetna
Took a flight around Denali from K2
Around Denali
Transportation museum Whitehorse
Richardson Highway
Glacier view camp
Hyder
Tunnel to Whittier, share with train and one way traffic
Studs are left hand thread where they go in the boss. 
Destruction Bay 
