Jacobs 26/160 split door vs full door

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I have a Jacobs 160 with a split door. Does anyone know if the split door was manufactured before or after the full door or were they both made at the same time? (Or were the split doors only used on the 160's?) I am trying to figure out which version is older.

Also, it is my understanding that Jacobs never produced a 160 but instead used the JSC 160 tags on the JSC 26. Is this correct?  Thanks