The Mishnah on today’s daf (=page) teaches that the things that disqualify kohanim do not disqualify levi’im; similarly, the things that disqualify levi’im do not disqualify kohanim. This is explained by the baraita as follows:
These laws, however, are limited by our Gemara only to the Tabernacle in the desert, based on the passage in SeferBamidbar (4:47) that restricts the age limitation only to carrying the Tabernacle. The Gemara concludes that in Shilo as well as in the permanent Temple, these age restrictions did not apply.
According to Sefer Yehoshua (18:1), the first established resting place for the Tabernacle was Shilo, where it stood until the war with the Pelishtim during the time of Eli the High Priest, as described in Sefer Shmuel (I, Chapter 4). As the Mishnah explains (Zevahim 112b), this was a permanent structure made with a stone foundation and the Tabernacle coverings as a roof. Following the destruction of the Tabernacle in Shilo, its remains were erected in Nov, as we learn from the story during King Sha’ul’s reign (see I Shmuel 21:7), and later we find that King Solomon sacrificed at the great altar in Giv’on (see I Melakhim, or Kings 3:4).
By mentioning Shilo and the Temple, the Gemara appears to connect the end of age regulation for the levi’im with the reality of a permanent structure that did not need to be carried. During those times when the aron was moved to place to place, i.e. Nov and Givon, however, the age restrictions were again in force. The Sifrei disagrees with this approach, and suggests that from the time that they entered Israel, the age restrictions were removed. The Rambam rules like this Sifreiwhen he writes that the age restrictions did not apply for all generations.