My orginal batteries in the 1978 IH 1086 lasted 14 years. These batteries had the IH logo on them but I"m sure they were made by someone else. I asked the dealer for them same batteries to replace them. I was told they no longer made that battery and if they did they would be high priced. I said it would be worth it if they last 14 years.
Replacments only lasted about 6 years or so.
Dads orginal batteries in his 1979 986 lasted 15 years as well. Same batteries as mine.