BAFFLE AS 2281564 - Caterpillar

Introduction
This Special Instruction contains information to correctly order a "Series B" replacement block. It also contains a list of additional parts required to complete the upgrade. The current "Series A" replacement block is being replaced with a newly designed "Series B" block (refer to Chart A). This change has been made due to the release of the new 3500 "Series B" Electronic Engine. The new "Series B" blocks went into production mid-year 1995 at which time the "Series A" blocks were canceled. The "Series B" blocks will now service both "Series A and B" blocks. Description of Change
The new block is not directly interchangeable with the former block without ordering additional parts. The changes to the new block and its related parts include the following.* A new cam bore diameter. The bore diameter has been increased in size from 92.00 mm (3.622 in) to 98.00 mm (3.858 in). Replacing the former block with the new block will now require the installation of thick-walled camshaft bearings.* The hole pattern and shaft diameter of the cam idler gear stub has changed. The new stub shaft has a three hole bolt pattern which will not allow the use of the former "Series A" stub shaft. The diameter of the stub shaft has also been increased from 75.00 mm (2.953 in) to 81.00 mm (3.189 in).* The rear gear assembly now uses an 8 pitch gear. The former 10 pitch gear cannot be used with the new block because of the larger stub shaft diameter. A new 10 pitch gear with a larger bore is available for replacing the gear in the former 10 pitch gear train. A new 8 pitch gear is also available for the newer 8 pitch gear trains.Ordering Information
Depending on the configuration of the engine, the parts required to upgrade the block to a "Series B" can vary. Refer to Charts B, C, D, E, F, and G for specific part numbers."Series A" Engine Blocks (Prior to serial numbers listed in Chart E)
To upgrade a "Series A" block with a 10 pitch rear gear assembly to a "Series B", order the parts listed in Chart B. "Series A" Engine Blocks (For Serial Numbers 4MJ150 - 161)
To upgrade a "Series A" block with an 8 pitch rear gear assembly to a "Series B", order the parts listed in Chart C. "Series B" Engine Blocks (For all serial numbers within this range 6PN, 7SM, 2BM, 3DM, 4GM, 8RM, 4TN, 7HM, 8EM, 6WN, 7RN, 8KN, 8CN, 9AN, and 6HN)
To upgrade a "Series B" block with an 8 pitch rear gear assembly, order the parts listed in Chart D. "Series B" Engine Blocks (For the serial numbers listed in Charts E, F, and G)
The following serial numbers and later serial numbers only require the replacement of the cylinder block to upgrade the engine. All other parts are directly replaceable. Rear Housing Rework Procedure
The new camshaft bearings cannot be removed through the front or rear engine housings. The current radius of the