MIAMI (AP) _ Ryder System Inc. has acquired for an undisclosed price Municipal Issuers Service Corp., which manages the nation's largest municipal bond financial guarantor, company officials announced Tuesday.

Municipal Issuers Service, based in White Plains, N.Y., provides financial analyses, marketing, administration and operational services to the Municipal Bond Insurance Association.

The association is a consortium of five insurance companies that guarantee principal and interest payments on debt obligations.

Members are Aetna Casualty and Surety Co., Fireman's Fund Insurance Co., Travelers Indemnity Co., Aetna Insurance Co. and Continental Insurance Co.

Miami-based Ryder has been in the insurance service business for 15 years and owns agencies in Florida and Alabama.

Ryder System is parent of a group of service-related organizations, including a transportation branch in the United States and Canada. The company is ranked ninth in assets, 14th in net income and 21st in revenue on Fortune magazine's list of the nation's largest 100 diversified service companies.

Its 1984 revenue was $2.5 billion.