UPDATE 2-Zucker to head new NBCU-Comcast venture -- sources

* Terms do not include a mandated exit for Zucker

* Comcast, GE still negotiating structure of new board

(Adds timeline, company comment, merger reasons)

By Jui Chakravorty

NEW YORK, Nov 10 Comcast Corp (CMCSA.O) and General Electric Co (GE.N) have agreed to make NBC Universal CEO Jeff Zucker the head of their proposed joint venture, but the structure of a new board is still being negotiated, sources familiar with the matter said.

The two sides have been in talks to reach a deal that would give Comcast a 51 percent stake in the NBC Universal venture, which would also house the cable networks now belonging to Comcast. They recently agreed to value NBC Universal at about $30 billion, sources previously told Reuters.

Under the terms being discussed, Zucker will lead the new entity, with no clauses for him to leave after a specific period, the sources said on Tuesday. They spoke on condition of anonymity because the details have not been made public.

Comcast declined comment. NBC did not return calls seeking comment.

As part of the proposal, NBC Universal would become a joint venture, 51 percent owned by Comcast and 49 percent by GE. Comcast would contribute around $4 billion to $6 billion in cash, as well as its collection of cable networks to pay for its stake.

There has been a lot of speculation about who would head the new company, especially since Peter Chernin -- the former president of News Corp (NWSA.O) -- has been advising Comcast.

The sources said Zucker would be chief executive, but no decisions had been made on what role Chernin might play, if any. Discussions about what the new board would look like are ongoing, the sources said.

One of the sources said progress made in the talks over the next few days are "critical" and would determine how quickly the deal gets done.

Vivendi, which owns 20 percent of NBC Universal and has to agree to a deal, is in talks with GE and is determined to get the best value for its investment. Those talks are progressing, but "going slow," one of the sources said.

Every year between mid-November and mid-December, Vivendi has to decide whether to exercise its "put" option to sell its NBC Universal stake.

This year, Vivendi is eager to dispose of its stake, which it acquired as part of a 2004 deal to create NBC Universal, and is negotiating the valuation with GE, sources have said.

Last week, Comcast and GE agreed on the valuation for NBC Universal, ironing out what had been a key obstacle in talks.

The valuation -- and the amount that Comcast will end up paying for NBC Universal -- are complicated, because the new company is expected to be able generate cash to pay down $9 billion in debt that would be added to its books as part of the deal. It would use that debt to buy the rest of the company from GE.

GE has negotiated a redemption option that would give it the right to redeem all or part of its stake in the new company in exchange for cash at the three-and-a-half year mark and at a seven-year mark, sources have said.

Also, the terms of the deal now allow Comcast's cash payment to be determined partly by NBC Universal's financial performance, sources told Reuters this week.

If the unit's performance worsens between the signing of the deal and the closing, Comcast could end up paying less.

Comcast has long wanted to buy media assets to create a content powerhouse spanning broadcast TV, cable and film. Chief Executive Brian Roberts said last month he would look at all opportunities in content.

Many of GE's shareholders have urged the conglomerate to offload NBC Universal, whose broadcast and cable networks, movie studio and theme parks are considered misfits among GE's mostly industrial operations. (Reporting by Jui Chakravorty Das; editing by Andre Grenon)