Dates for ThirukkuRaL & Gita

[Yashwant Malaiya]

P.Chandrasekaran wrote:
.. "thirukkuRaL" written no later than Gita ..

There is perhaps no way to be sure of the chronological
sequence, but what are the sources that suggest

- definite early/late bounds
- likely dates

for the two books?

Also, I am curious about available manuscripts of
the thirukkuRaL and if they have been critically
compared.

I have heard about some shlokas of Gita that are
not found in the common version. Does anyone have
those?

Yashwant