Gemara

4b (R. Chiya): There are 24 Avos Nezikim: a thief's payments of Kefel, four or five (times the value of an animal sold or slaughtered after it was stolen), principal...

5a (R. Avahu): They are all called Avos because they pay from Meitav.

(The Torah teaches about Meitav regarding a Mu'ad ox.) An extended Gezeirah Shavah teaches this about all 24. Regarding every one, it says "Tachas", "Nesinah", "Yeshalem" or "Kesef".

10b - Question (Rav Kahana): Without "the carcass will be to him", could we really think that the damager must keep the Neveilah?! A Beraisa learns from "he will return" that any Shavah Kesef may be given, even bran. The damager can pay with any carcass if he wants, all the more so with the victim's carcass!

Answer (Rav): The verse teaches that the victim suffers any loss in value of the carcass from the time of damage until the payment.

11a (Shmuel): We do not evaluate (the carcass' value towards the payment) for thieves or robbers, only for damagers. My father and I say, even for a borrower.

The Halachah is, we evaluate for a borrower, but not for thieves or robbers.

Bava Basra 92a (Rav): If Reuven sold an ox to Shimon and it was found to be a gorer, the sale is mistaken (and therefore void).

92b - Question: If Reuven has nothing else to give Shimon in place of the money he owes, he may give him the ox!

Rishonim

Rif (1b): They are all called Avos because they pay from Meitav.

Rif (5a): We do not evaluate for thieves or robbers, only for damagers, and for a borrower. We evaluate how much the Kli was worth before it broke. The owner takes the broken Kli, and the borrower compensates the decreased value.

Nimukei Yosef (Sof 4b, citing the Ramah): This is if the thief has money. If he has no money, he may use the shards towards payment. A Gezeirah Shavah teaches that a thief is among Avos Nezikin, which pay with Meitav; they may also pay Metaltelim. We do not learn evaluation from damages. A thief or robber acquires through Shinuy (changing the object); he may keep it and force the owner to accept money. We evaluate what the shards are worth at the time of collection; the thief suffers any depreciation. A damager or borrower does not acquire through Shinuy; he cannot keep it and force the owner to accept money. We evaluate what the shards were worth at the time it broke; the owner suffers any depreciation. If a thief did not make a total Shinuy to acquire it, he returns it and fulfills "he will return the theft that he stole.' He need not give compensation if it broke by itself. If he broke it, he pays like a damager. If a he made a total Shinuy, even b'Ones, he must pay a total Kli. He cannot return the shards.

Nimukei Yosef (2a): The Meforshim rule like Rav Papa, that all Metaltelim are Meitav. The Ramah says that one may give bran only when he does not have money. The same applies to a borrower or one who must return money of a mistaken sale, who is like a robber, who is one of the 24 Avos Nezikin.

Gra (CM 354:12): We learn from Bava Basra that regarding a mistaken sale (which is like a thief), if he has money he must pay money.

Rambam (Hilchos Geneivah 3:11): A thief pays principal, Kefel, and four or five from his Metaltelim. If he has no Metaltelim, we collect from Idis, like other damagers.

Rosh (1:11): A thief may not pay with a Neveilah or shards, for it says "Chayim Shenayim Yeshalem". A robber may not pay with them, for it says "he will return the theft that he stole' - it must be like he stole. However, he may return the monetary equivalent. It is just as good, for it can be used to buy a new one.

Hagahos Ashri: R. Shmuel says that he may give even bran, carcasses or shards. However, the owner need not accept the loss (that the carcass deteriorated after death). R. Yitzchak defends Rebbi from the Yerushalmi.

Poskim

Shulchan Aruch (CM 348:5): If a thief has Metaltelim, we collect for the theft from them. If he has only land, we collect from Idis, like other damagers.

SMA (5): Any Metaltelim may be paid, even bran, even for damages, even if he has money.

Gra (19): This is like the Rambam. The other Poskim argue (and say that he may give Idis if he wants).

Shulchan Aruch (354:1): If a thief stole a Kli, and he broke or diminished it, or it broke or diminished by itself, he may not return the shards and the decreased value. Rather, he keeps the shards, and gives the owner a complete Kli or its monetary equivalent.

SMA (10): A damager may return the shards, because it says "veha'Mes Yihyeh Lo". Regarding a thief and robber, it says "Chayim Shenayim Yeshalem" and "he will return the theft that he stole' - like he stole.

Bach (5): This is like Rashi and the Rosh. Semag explains like R. Shmuel, that a thief may return the Neveilah. The owner need not accept the depreciation after death, unlike a victim of damage, who must accept it. R. Chiya listed a thief among Avos Nezikin to teach that he pays like damages. If so, he may pay even with bran. Tosfos brings both Perushim, in different places. Hagahos Ashri did not decide like either Perush. Since there are different opinions, we do not force a Muchzak to pay. The thief can give the Neveilah or shards and the decreased value, unlike the Shulchan Aruch.

Rema: This is if the thief has money. If he has no money, the shards are no worse than Metaltelim.

Gra (12): There are three opinions. The Ramah allows a thief to pay with the shards only if he has no money. Tosfos (Bava Metzia 96b DH Zil) allows a thief to pay with the shards, even if he has money. Tosfos and the Rosh (Bava Kama 11a DH Ein and 1:11) hold that he may not pay with the shards, even if he has no money.

Question (Shach 7): This is like the Ramah. We do not follow the Ramah! And if the Rema ruled like the Ramah, he should have permitted the thief to pay with the shards even if he has money. The Ramah himself does not allow a damager to pay Metaltelim if he has money. We rule unlike this (419:1). We must say that the Rema learns from the Ramah that if the thief has no money and cannot give a complete Kli, if the owner wants Metaltelim the thief may pay with the shards, for they are no worse than other Metaltelim.

Shulchan Aruch (419:1): If a damager has Metaltelim, even bran, we do not take land. Even if he has money, he may pay with bran, for all Metaltelim are Meitav.