Hi Larry, I am pleased to assist you. This brand new alternator (66445.1F) is a 100-amp, single-wire alternator with an internal regulator. It features a GM 10si-style case and is designed for Ford V8 engines ranging from 260 to 460 cubic inches, including the 1962–1987 Mustang's 320 engine. If your Mustang belongs to this group, this should work effectively for your vehicle. Use the link below to order while the part is in stock. I hope this helps, and enjoy shopping! https://www.carparts.com/alternator/proform/p75664451f?can=CPGG4850_CSQA_20250401

Hi Tim, thanks for initiating contact. While specific measurements for this alternator are not readily available in the search results, general dimensions for similar high-output alternators typically range as follows: Length: Approximately 8 to 10 inches Width: Approximately 6 to 8 inches Height: Approximately 6 to 8 inches Mounting Hole Spacing: Often around 3 to 4 inches, depending on the specific mounting design These dimensions may vary slightly based on the specific model and configuration of the alternator. if you're interested, you can use the link below to order while the part is in stock. Your order will come with a 30-day post-purchase price match guarantee. Enjoy shopping! https://www.carparts.com/alternator/proform/p75664451f?can=CPGG4850_CSQA_20241001