I'm almost sure it's 36 thousands, since we're talking about 36 not 1. But I'm in doubt because 36 already indicates that it's more than 1, so maybe, just maybe, it could be 36 thousand?
You can have thousands of soldiers, but when you are being exact, you have n thousand of them. same for hundreds, dozens or millions.
To explain a bit: the word 'thousand' is part of the number, which is modifying the noun (whatever it is that you're counting). Because the number is greater than 1, the noun takes the plural form, but the number itself does not change form. Would you say "sixteens men" because sixteen is greater than one? I certainly hope not. "Sixteen thousand" is still a number, just like "sixteen" is; just because it's expressed in two words doesn't make you treat the individual words differently.
When number + thousand precedes a noun (e.g. Dollar, Rupee or Taka), it already acts as a compound adjective which cannot take plural 's'... but when it doesn't work attributively, it's of hazy currency in south Asia: d govt. Sanctioned a bill of 50 crores/ laks/ thousands (besides crore/lak/thousand)