If there is no serial number (and no evidence of ever having one) it is likely pre-68. Serial numbers were not required pre-68.
IIRC these were savage/springfield made for Montgomery Wards. Western Field was Wards "trade name" for guns. This was similar to Sears and the "Ted Williams" brand.
SLLR means it is intended for Short, Long and Long Rifle cartridges.
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