1. Sorry I don't have info as to year of manufactuer. When I retired I tossed all my forklift lift stuff in the trash including my serial number guide. But my 'guesstiamte" it is early 1970ish at best good possibility it is older as the engine was renamed to the G-153 and any referenced to the Buda company was gone when I joined the company in 1967. After A-C moved to a the Matteson Lift truck plant in 1970 they started using a s/n system with alpha & numerical numbers to indicate what plant the product was built in. The s/n you provided does not reflect that change.
2. Reasons for discontinuing the use of the A-C engine was for a couple of reasons - the main one was increase in cost (about doubled). Production volume in engine manufactuering is everthing to keep cost down. The A-C Engine Divison supplied a lot of generator sets that used the same engines as the lift trucks to the US government in support of the Vietnam Conflict. When the US withdrew from Vietnam, production volume fell off, cost went up. The lift truck division was they only significant user of this engine. The other reason corporate, David C. Scott, President, was looking for extra cash flow to support a five year mega buck "coal gasification" project that never panned out and cost reduction was the name of the game for all A-C operations as directed by corporate - they picked the F163/225 because it was cheap (marketing had no input but later did get blamed for loss of market share). At that time - only Clark & Yale had overhead valve engines & Cat was coming out with one in their lift trucks so the engineers & production folks said the "majority" of lift trucks supplies are using the Contiental wafle head engines. Talk about cutting off your nose to spite your face. David C. Scott screwed up Colt Industries before he came to A-C.