Hi Wayne, I'm glad to assist you. The matching alternator is a Bosch brand 120 ampere with a 6-groove pulley (1991 Dodge Dakota 6/8 cylinders). Grab our sale offer and click the link below to buy it today. Happy shopping! https://www.carparts.com/details/Dodge/Dakota/Bosch/Alternator/1991/Base/8_Cyl_5-dot-2L/BSAL6510X.html?can=cpje1043_CSQA_20240329 (with 6 groove pulley)

Hi Nathan, I'm glad to assist you. As per checking, that bolt size is never mentioned anymore since this is a direct fit guaranteed to fit part for the 1990 to 1991 Dodge Dakota, B150, B250, B350, D150, D250, D350, W150, Ramcharger, 3.9L, 5.2L, 5.9L, with 90amp alternator. The dimensions of the bolt hole mounting is not noted anymore since you have to accurately select your vehicle application(year, make, model, submodel and engine size) and the resulting search would show the exact parts designed for that specific vehicle application only. And you have to read the fitment information as well to check the specific details noted. Please click the link below to order this part today. A call to the dealership for that bolt size should be very helpful as well. I hope this helps. Happy shopping. https://www.carparts.com/alternator/quality-built/mpa15690?can=CPJE1043